Creative Education Games

Candles and Oxygen

2010-12-10T19:06:00.000-08:00

In addition to any fire turns living creatures need oxygen
through these exciting games or we can prove that the fire needs air.

Materials and tools:
1. candles,
2. plates,
3. glasses,
4. matches,
5. dyes.
6. estimated cost of $ 12.5

Procedures:

1. First you turn on a candle and place on plate, then take the glass and close the wax using the glass
2. See what happens .. yes ... the candle outages.
3. To enliven the atmosphere if done in class before the candles on the lid invite students to do hipoitesa with questions.

After the experiment above, we proceed with the following experiment in which we can prove that there really air out when the candle of life.
Still with candles and dishes before, the input of water into the dish, give it a little dye to facilitate observation. Turn on the candle, and then do the same experiment with the above, observe what happens .... and ... .... water is sucked into a glass dish.

Rising water in a glass to prove that that air is lost because it is used in the combustion process so that the empty space is replaced by water.

Naked Egg

2010-12-03T18:47:00.000-08:00

Ever see the contents of the egg without breaking?

nah through the following experiment where you can see how to view the content without breaking eggs .. how easy ..

egg naked let's get started:

Tools and materials:
1. eggs
2. glass
3. citric acid or vinegar

Procedure:
1. Fill glass with water until half full.

2. Add 2 tablespoons of citric acid and stir until dissolved

3. Enter a quail egg into a glass and let some time

4. This experiment can also use the vinegar solution eat

Oooo .. What happened ..

Outer skin to peel eggs and turn into white.

Let's find out yes ...

Egg shell is made of a substance called calcium. This substance will change when mixed with citric acid. The result is carbon dioxide gas. That is why you see no bubbles in the glass. Gas is more and more. Because it is lighter than water, gas moves upward, lifting egg.

Change starts from the outermost egg. That is why the skin with brown spots off first. As a result, the egg into the net. If the egg continues to be soaked, then the skin will come off. well now you try to soak the egg task longer what will happen.

Note: to facilitate a mixture of citric acid can be replaced with regular eating vinegar

Form a Gas

2009-02-15T21:24:00.001-08:00

Inflate a balloon without blowing into it, or using a pump! You can do this by making a gas and then getting it to go into a balloon. The gas is called carbon dioxide. It is this gas which forms the bubbles in soda water and fizzy drinks.

Materials:
1. Vinegar
2. Sodium Bicarbonate
3. Balloon
4. Funnel
5. Narrow-Necked Bottle

Procedures:
1. Pour some vinegar into the narrow-necked bottle until it is about a quarter full.
2. Using the funnel, fill the balloon with sodium bicarbonate powder.
3. Stretch the neck of the balloon over the neck of the bottle. Do not let the sodium bicarbonate escape from the balloon.
4. Lift the balloon so that the sodium bicarbonate falls into the bottle. The vinegar begins to fizz and the balloon slowly starts to inflate. The vinegar reacts with the sodium bicarbonate to release bubbles of carbon dioxide gas. As more as gas forms, its pressure increases and the balloon expands.

Exploding drink
Shake a bottle of fizzy drink then unscrew the cap. The drink fizzes up out of the bottle! Carbon dioxide gas is dissolved in the water in the drink. It is kept under pressure in the bottle. When you unscrew the cap, you reduce the pressure and the gas bubbles up out of the water.

Discovery the Gasses in the Air

2009-02-15T21:21:00.000-08:00

Put out the candle without blowing on it or touching it. When you do this experiment, you show that air is a mixture of invisible gases. One of these is especially important. It is oxygen which is used when things burn and produce energy.

Materials:
1. Candle
2. Coloured water
3. Glass jar
4. Bowl and Candle holder

Procedures:
1. Put the candle in the holder and place it in the bowl. Then pour in the water.
2. Ask an adult to light the candle. Then place the jar over it. Leave it for a little while.
3. At first, the water level in the jar rises, and then the flame suddenly goes out!

Air and Energy
Like other cars this racing car gets its energy from petrol burning in its engine. Burning fuel provides most of the energy we use for heating and powering machines. This process uses oxygen, which comes from the air around us.

Weight Some Air

2009-02-15T20:52:00.000-08:00

When something is very light, people often say “It’s as light as air”. But air is not light at all. Do this simple experiment to show that air is really quite heavy.

Materials:
1. Balloon pump
2. Two balloons
3. Rubber band
4. Two Drawing Pins
5. Long thin piece of wood
6. Ruler
7. Pencil
8. Sticky tape
9. thread

Procedures:
1. Use the ruler to find the centre of the wood. Then mark it.
2. Push a drawing pin into each side at the centre mark.
3. Tie the thread to the middle of the rubber band.
4. Fix the loops of the rubber band around the drawing pins. Lift the wood by the thread. It should balance.
5. Tape one of the balloon to one end of the wood.
6. Tape the second balloon to the other end of the wood. Check that it still balances. Then remove one balloon and blow it up.
7. Tie the neck of the blown-up balloon and attach it to the wood in the same place as before. The balloon make the wood lose its balance.

Drinking with a straw.
When you drink through a straw, the weight of the air helps you. The air above the drinks pushes on the surface of the liquid. As you suck, it forces the liquid up through the straw to your mouth.

Crush With Air

2009-02-05T19:56:00.000-08:00

Make a plastic bottle collapse without touching it! The air does the job for you. You cannot feel air, but it presses against every surface. This is called “air pressure”.

Materials:

1. Ice
2. Funnel
3. Hot and Cold Water
4. Plastic soft drinks bottle
5. Bowl

Procedure:

1. Stand the bottle upright in a bowl. Pour the hot water into it and leave it for a short time.
2. Screw the top on the bottle. Lay the bottle in the bowl and pour ice and cold water over it. Then stand it up.
3. The bottle collapses! As the warm air inside the bottle cools, it exerts less pressure. The air outside is stronger and crushes the bottle.

Seal with Air

2009-02-05T19:51:00.000-08:00

Stop water falling out of an upturned glass. A card can stick to a glass and keep the water in it, as if by magic! Air pressure forces the card upwards, against the glass. The pressure is strong enough to stop the weight of water pushing the card away.

Materials:

1. Thin flat card
2. Glass
3. Water

Procedure:

1. Hold the glass over a sink or a basin. Carefully pour some water into the glass.
2. Place the card on the glass. Hold down so the eard touches the rim all the way around.
3. Still holding the card turns the glass upside-down. Let go the card. The water stays in the glass!

Investigate Water Power

2008-08-08T00:46:00.000-07:00

Materials:
- Foil Dish
- Scissors
- Pencil
- Tape
- Piece of string
- Weight of some sort

Procedure:
1. Make 8 equally spaced cuts around the edge and towards the centre of the plate. End each about 1 cm from the centre.
2. Fold one edge of each to make small ledges.
3. Puch a hole in the middle and push the pencil through. Tape it into place.
4. Let the pencil rest between your fingers and thumbs and hold the wheel under a stream of water (running tap). (What happens when the rate of flow is increased or reduced?)
5. Tie a piece of string to the pencil and attach the weight to the other end. The water wheel should wind the weight up to the pencil. (How much can be lifted? What happens when the load is too heavy?)

Investigative Flight

2008-08-08T00:43:00.000-07:00

Materials:
- Paper
- Scissors
- Straw
- Tape
- Ruler

Procedure:
1. Cut a piece of paper 5 cm by 15 cm. Hold it against your lower lip.
2. Now blow across the surface. What happens?
3. Use another piece of paper and this time bend it to the shape of a wing, curved on top and flat at the bottom. Tape the ends together.
4. Put a straw through the wider end and let the paper hang down.
5. Blow over the wing. What happens?

Procedure:
1. Cut two strips of paper; one 2 cm by 24cm and the other 1.5 cm by 18 cm.
2. Make each strip into a loop by overlapping the edges by 1 cm and taping them.
3. Insert a straw into the two ‘pockets’ you have made.
4. Throw it like a spear. Compare it with throwing a straw on its own.

Dragon

2008-08-08T00:40:00.000-07:00

Dragon by The Tail

Player line up one behind the other grassping the waist of the person in front. The person at the front of the dragon has to try to touch the person at the end of the tail, dragging the dragon as he or she tries to do so. Anyone who lets go is out of the game.
When the person at the front succeeds in touching the person at the end, he or she goes to the end of the line and the next person becomes the head.

Dragon Tiggy
When a person is tagged by ‘he’, the two join hands and so on until all players are joined to form one long dragon.

Dragon Board Game
Make a board game to follow the sequence of a favourite dragon story. Or, make a ‘dragons and ladders’ game. Or make a trail game to find the dragon’s treasure. Or, make up a variation of Battles.

Tailing a Suspect

2008-06-25T19:25:00.000-07:00

Sometimes during an investigation, a detective has to tail, or follow, a suspect. The suspect may make contact with other suspects or might lead the detective to more evidence. Try the following activity at school or another safe location to test your ability to tail a person.

Materials

- Notebook
- Pen or pencil
- Watch
- Several helpers

Procedure
1. Gather several helpers together. Inform them that at some point during the next week, you are going to tail one of them as part of an experiment. (Telling them that you are going to tail them makes your task more difficult but will avoid their embarrassment.)
CAUTION: Tail the person at schol or in another safe location, such as a party. Never wander around alone.
2. Choose a day and select one person to follow for one hour. Use your notebook to record notes of his or her activities and any people the person encounters. Record the time for all notes you make.
3. When you have finished tailing the person, review your notes. Are there any activities that surprised you? Could you tell exactly what happened during each encounter with other people? Did the person figure out that you were tailing him or her?

More Fun Stuff to Do

Detectives seldom follow a suspect by themselves. They usually work in teams to prevent the suspect from getting suspicious. Often a second, third or even a fourth detective will pick up the trail where the previous detective leaves off. Try using a team to trail one of your helpers.

Explanation

It is difficult to tail a person without being noticed. If a suspect sees the same person, especially a stranger, over and over again, the suspect’s brain is alerted that something out of the ordinary has happened. He or she will become more cautious and will try to see whether someone is indeed tailing him or her. This is why the police use teams to follow suspects. One person will follow the suspect for a short time, then a second, third, or eve a fourth detective will pick up the trail. The suspect does not see the same person, so the suspect’s brain is not lerted that something unusual is happening.

Tailin a suspect is a form of surveillance. The term surveillance comes from the French word surveiller, which measn “to watch over.” Police practice surveillance for many reasons. They may watch a suspect’s home or place of work in order to gain information or even to catch the suspect. This is sometimes called a stakeout. They may trail a suspect to get other information, such as a suspect’s habits, daily routine, personal contacts, and place of work, home address, or type of information used.

The detective can be use the information gathered from observing a suspect to form a hypothesis or theory about the suspect, just as a scientist uses information to form a hyphotesis about an experiment. For example, if a suspect meets with the same person ath the same time every day and is seen passing slips of paper to that person, then the detective might make the hypothesis that the suspect is involve in a gambling operation and that the slips ofpaper are betting slips. The detective will then continue to investigate to determine whether that hypothesis is correct, in the same way that a scientist will test a hypothesis through experimentation.

Interviewing Witnesses

2008-06-25T19:15:00.000-07:00

During an investigation, much of a detective’s time is spent interviewing witnesses and questioning suspects. If everyone tells the same story, a detective can feel confident that he or she has learned the truth about a crime. But often people lie, or they believe they are telling the truth but are mistaken. Try the following activity to see how good you are at interviewing witnesses.

Materials

- Copy of the picture on crime scene
- Watch or clock
- Pen or pencil
- Notebook
- Several helpers

Procedure

1. Have all of your helpers but one leave the room.
2. Give a copy of the picture on crime scene to the helper.
3. Using the watch or clock, give your helper 1 minute to look at the picture, than take the picture away.
4. Ask your helper what he or she remembers about the picture. Ask questions like “How many people were in the picture?” or ”Was there anything unusual that you noticed?” Record the answers in your notebook.
5. Repeat the procedure with each of the remaining helpers, making sure that the helpers do not hear each other’s answer to your questions.
6. Compare the comments that the helpers made. How many details were mentioned? Did some statements conflict with other statements?

More Fun Stuff to Do

Stage a pretend crime during a party or family gathering, and see wether any of the guests can figure out who did it. You could have someone “steal” some books off a shelf or remove a candlestick. At some point after the crime, choose several guests as witnesses and question each in a separated interview. How did their observations compare? Were their observations good enough for them to figure out who took the books?

Explanation

When interviewing witnesses to a crime, there are several questions that detectives ask to get a description of and information about the suspect. Some typical questions include: What is the sex, race, and approximate age of the suspect? What is his or her height, weight, color of hair and eyes, and complexion? Did you notice any physical scars or marks? Did the suspect wear glasses or have facial hair? What was the voice like? What was the suspect wearing? What did the suspect do?
Interviewers must listen for unexpected information. Often the question will cause the person who is being interviewd to implicate another person, meaning the person will reveal, by accident or on purpose, that someone else was involved in the crime.

Interviewers should remain impartial when they interview witnesses. This means they should not reveal their own opinions or feelings during the interview. Also must be careful not to lead a witness to say something that is not true.

Interviewing witnesses and other methods of crime detection are similar to scientific investigation in general. Scientist brings their own thougts and opinions to their experiments. Often they want an experiment to turn out a particular way, so it is difficult for them to remain impartial. This explains why two scientists, seeing the same information, can come to two opposite conclusions. Each bends the information to support his or her own views. Whether investigating crimes orperforming experiments, scientists must always keep an open mind and be ready for unexpected data.

The Scene of the Crime

2008-06-25T19:06:00.000-07:00

It’s no exaggregation to say that following proper procedures during the first investigation of the crime scene can make the difference between a solved crime and an unsolved one. Try the following activity to learn some of the procedures performed at the scene of a crime.

Materials

- Your bedroom or another room of your house
- Several sheets ofwhite paper
- Marking pen
- Masking tape
- Pen and/or pencil
- Notebook
- Camera (optional)
- Tape measure
- Several plastic bags

Procedure

1. Pretend a crime has been commited in the room you’ve selected. Suppose something has been stolen from the room.
2. Secure the scene of the crime. With a sheet ofpaper and themarking pen, make a sign that reads, POLICE INVESTIGATION, DO NOT ENTER.Use the masking tape to tape the sign across the entrance to the room.
3. Begin to record your observations of the room in your notebokk. Remember, when investigating a crime scene, you cannot knowwaht is important and what isn’t. You need to record everything you find. If you have a camera, take severalpicture of the room.
4. Use another sheet of paper and the pencil to make a sketch of the room. Measure the dimensions of the room using the tape measure, and record the measurements in the sketch. Draw in window and door locations and the placement eny funiture.
5. Examine the roomcarefully. Record your observations in your notebook. Add to your room diagram the location ofany important items you find.
6. Begin to look for physical evidence may include hair and fibers, a glass or other object that could contain fingerprints, a diary or notebook, or anything else you think might be important. Examine the wastebasket. What do its contents tell you?
7. Save each piece of physical evidence in a plastic bag to examine later using the procedurs you’ll learn.

Explanation

The first duty at the crime scene is to secure the scene of the crime. This is usually done by the first police officer to arrive. If a person is badly injured at the scene, the officer will give assistance and call for medical aid.

Many crimes are investigated by the police officer on duty, but in more serious crimes, such as those that involve serious injury or the loss of expensive objects, a detective is often assigned to the case. A detective has usually received additional training, beyond that given to a police officer, in how to investigate a crime. When the detective arrives, he or she begins to record the scene of the crime by taking photographs, making sketches of the site, and taking notes.

The detective or members of a special forensic scinece team collect physical evidence. Physical evidence cololected from the scene of the crime is stored in labeled bags or containers, and then sent to the forensic science laboratory for later investigation.

The investigators at the crime scene must be very careful to collect and preserve allphysical evidence and to record all of their observatios. These data will be used later to solve the crime.

Detective Science in Action

You never know when something unusual found at the scene of a crime will be important to an investigation. In 1994 Dr. Gail Anderson, a forensic entomologist (a scientist who studies insects), was asked to aid wildlife enforcements officials who were trying yo put a stop to poaching (the killing of wildlife either without a license or out of season). In British Columbia, Canada, poachers often kill black bears and take their gallbladers, small internal organs that are valuable in certain cultures.

Investigators found insects on several black bears that had been killed by poachers. Dr.Anderson knew that insects have specific stages of development, from egg to adult. By examining the stage of the insect’s development and working backward, she was able to approximate the actual date the bears were killed. Wildlife officials could then focus their investigation on individuals who were in the area on that day. The insects found on the bear’s eventually led to the arrest of the poachers.

Mystery Box

2008-06-09T16:21:00.001-07:00

Good observation skills involve all the scenes (the ability of the brain and nerves to react the world around us through sight, hearing, smell, touch, and taste). Sight is just one of the senses. What a forensic scientists, detective, or witness hears, smells, feels, or tastes may also be important clues. Try the following investigation to sharpen your nonvisual observationn skills.

Materials

- empty shoe box or similar box with lid
- various objects made from different materials-such as a rubber ball, a roll of toilet paper, a metal jar lid, a bar of soap, a plastic toy, a piece of fruit such as an apple, banana, or orange, etc—gathered by your helper with out your knowledge
- helper

Procedure

1. Leave the room.
2. Have your helper put several of objects in the shoe box and put the lid in place.
3. Return to the room and, without opening the box, try to guess how many objects are in the box and what the objects are made of. If possible, guess what the objects are. You can tilt, gently shake, and smell the box to help you.
4. After you have made your predictions, open the box and see how well you did. What objects were the easiest to determine? What objects were the hardest to determine?
5. Repeat the activity with other objects. Give your helper a turn at guessing.

More Fun Stuff to Do

To develop your sense of touch, have a helper first blind fold you and then put several objects in front of you. Touch the objects, but do not pick them up. Can you identify them? Without removing the blindfold, pick upthose that you could not identify. Can you tell what they are now? Remove the blindfold and see how well you did. Repeat the activity with other materials, but this time have your helper wear the blindfold.

Explanation

Forensic scientists and detective must use all five of their sense when investigating a crime. They often use the sense of sight to observe the scene of the crime and record what they see. But often the other four senses--hearing, smell, touch, and taste--will give a forensic scisntist information that may or may not be important evidence or clues. For example, that faint smell or bitter almond in a dringking glass might mean cyanide poisoning. Three loud bangs heard by witnesses could be gunfire or just a car misfiring.

Here is an exercisethat you can use to improve your other senses. Sit on a park bench on a warm spring day. Close your eyes and observe what is happening around you. Can you identify five sounds that you hear? Can you identify three smells?

You Are The Detective

2008-06-09T16:19:00.002-07:00

Your mother picks you up from school one afternoon. Before returning home, she has to stop at the bank to make a deposit. The two of you stand in line at the bank, waiting for your mother to be helped. Suddenly, one of the tellers screams, “We hav been robbed!” What did you see while you were standin in line that might help with the investigation of the crime? Use your powers of observation to see what you remember.

Materials

- Picture on the stage
- Timer
- Pen or pencil
- Paper

Procedure

1. Observe picture on the stage for exactly 30 seconds. Look at everything that you thing might be important.
2. After 30 seconds, cover the picture and answer the question below. Write the answers on the sheet of paper.
3. How observant were you? Compare your answer to the picture.

Questions

1. What time was it on the clock?
2. What was the date?
3. Describe the person at the front of the line. Was it a man or a woman? Was he or she wearing a hat? What kind of clotes was the person wearing? Could you tell how tall the person was? Did he or she have any distinguishing features?
4. Did you notice anything unusual in the picture?

More Fun Stuff to Do

Repeat the activity, but this time put the picture away overnight and try answer the questions the next day. How good is your memory of the picture after 24 hours?

Explanation

When you observe, you create in your mind images of what you see. But what you see also has to be transmitted to your brain and stored in order for you to remember it later. As you found out in this activity, there is a lot of room for error in this process. When you first observed the picture, maybe you didn’t notice certain details. Or may be you saw details but didn’t think they were important to make a point of remembering them.

If you did More Fun Stuuf to Do activity, you also know that time affects memory. Much of what we observe is stored in our short-term memory, and we remember it only for a few hours, or may be only a few minutes.

If we store observations in our long-term memory, however we may remember them for years. Repeating something over and over help us remember it. Another helpful way to remember something is to associate it in our minds with something else. For example, most people would not be able to draw a map of Poland from memory. But if asked to draw a map of Italy, many people would be able to draw a fairly good sketch. Why? Because the shape of Italy resembles a boot. The shape of Italy sticks in our mind because we associate it with a common shape.

You can improve your powers of observation by doing the following exercise. Look at a department store display window for 30 seconds, then turn away and write down everything that you saw. Compare your notes with the real thing and write down the items that you left out. If you keep practicing this, your powers of observation will greatly improve.

Counterfeiting

2008-06-09T16:19:00.001-07:00

We all know what dollar bill looks like, but how many of us have really examined one carefully? Trythe following activity to investigate how fake bills, called counterfeit bills, are detected.

Materials

- picture of counterfeit bill
- $1 bill
- pencil
- paper

Procedure

1. There are at least twelve things wrong with the $1 bill on the sample. Examine the picture and see how many errors you can find. Write down your answers.
2. After you have found as many errors as you can, compare the picture to the real $1 bill. Write down any additional errors you notice.
3. Compare your answers with the list on the next page. Did you find the more errors listed?

Explanation

To counterfeit means to make a copy of something with the intent to trick or deceive. It used to be very difficult to counterfeit paper muney. The counterfeiter had to make special plates, or replicas, of each side of the bill being counterfeited. There were many places where mistakes could be made. The wrong hair on the president or an error in the serial number could ruin moth of work.

With the rise of color copiers, however, counterfeiting money is now easier. New high-speed, high-quality laser copiers are a quick and simple way to duplicate money. To combat counterfeiting on this new generation of copiers, the U.S government is now printing money on special paper that can’t be purchased by anyone but the government. Counterfeit money will not only look different, but feel different, too. The Canadian government has begun using a high-tech solution to stop counterfeiting. They’ve started placing holograms on their money, similar to the ones on credit cards.

There are many document besides paper money that can be counterfeited. With the aid of copiers, payroll and other checks are commonly forged. But even nonpare items, such as credit cards, can be copied. As with money, holograms have been added to credit cards to make them harder to forged. And special dyes that can only be seen under ultraviolet light are used to add pictures and words to the front of the credit card.

Slant Analysis

2008-06-09T16:18:00.000-07:00

The slant of a signature is another way to compare handwriting. Perform your own slant analysis to master the technique.

Materials

- pen or sharp pencil
- sheet of white paper
- sheet of tracing paper
- ruler

Procedure

1. Write your name two times on the sheet of white paper.
2. Place the tracing paper over your signature.
3. Use the ruler to make a slash through each letter in each signature so that each slash has the same slant as the letter.
4. Compare the two series of slanted lines. Are they similar?

More Fun Stuff to Do

Write your name on another sheet of paper. Have a helper forge your signature below your real signature. Make a slant analysis. How do the two signatures compare? Could this methode of handwriting analysis prove that your helper’s signature was forged?

Explanation

All four methode of handwriting analysis--top-of-letter, bottom-of-letter, spacing, and slant—help forensic scientists examine and compare handwritten documents. Often forensic scientists perform several forms of analysis on the same handwriting to confirm that it is a forgery. These methodes can be done more accurately by using computers. A sample signature can be scanned and placed in the computer’s memory for later comparison.

Detective Science in Action

One of the most famous kidnapping cases in the United States happened in 1932 when the baby son of Colonel and Mrs. Charles Lindbergh was kidnapped. Colonel Lindbergh was the first person to make a solo airplane flight across the Atlantic and was widely considered a hero. The conviction of Bruno Richard Hauptman, arrested for kidnapping the Lindbergh baby, was based in part on the testimony of handwriting experts. They compared the writing on the ransom note with handwriting samples that the police obtained from Hauptman after his arrest.

Spacing Analysis

2008-06-09T16:17:00.000-07:00

Experts also compare the spacing between words and letters to analyze and identfying handwriting. Try a spacing analysis to see how this technique is done.

Materials

- pen or sharp pencil
- sheet of white paper
- sheet of tracing paper
- ruler

Procedure

1. Write your name two times on the sheet of white paper.
2. Place the tracing paper over your signature.
3. Make a small mark on the tracing paper at all of the low points of the beginning and ending of each letter in each signature.
4. Use the ruler to join the righmost mark of each letter to the leftmost mark of the next letter for each signature, creating a series of short lines between the letters.
5. Compare the two sets of lines. Are they similar?

More Fun Stuuf to Do

Write your name on another sheet of paper. Have a helper forge your signature below your real signature. Make a spacing analysis. How do the two signatures compare? Could this methode of handwriting analysis prove that your helper’s signature was forged?

Bottom-of-Letter Handwriting Analysis

2008-06-09T16:09:00.000-07:00

Another way to analyze handwriting is to analyze the bottom of the letters.

Materials

- pen or sharp pencil
- sheet of white paper
- sheet of tracing paper
- ruler

Procedure

1. Write your name two times on the sheet of white paper.
2. Place the tracing paper over your signature.
3. Make a small mark on the tracing paper at all of the low points of each letter in each signature.
4. Use the ruler to join each mark to the one next to it, creating a zigzag line across the bottom of each signature.
5. Compare the two zigzag lines. Are they similar?

More Fun Stuff to Do

Write your name on another sheet of paper. Have a helper forge your signature below your real signature. Make a bottom-of-letter analysis. How do the two signatures compare? Could this method of handwriting analysis prove that your helper’s signature was forged?

Top-of-Letter Handwriting Analysis

2008-06-09T00:45:00.000-07:00

Each person’s style of handwriting is unique and can be identified, often even if a person is trying to disguise his or her handwriting. Try the following activity to see one way handwriting is analyzed.

Materials

- pen or sharp pencil
- sheet or white paper
- sheet of tracing paper
- ruler

Procedure
1. Write your name two times on the sheet of white paper.
2. Place the tracing paper over your signature.
3. Make a small mark on the tracing paper at all of the high points of each letter in each signature.
4. Use the ruler to join each mark to the one next to it, creating a zigzag line across the top of each signature.
5. Make a top-of-letter analysis by comparing the two zigzag lines. Are they similar?

More Fun Stuff to Do

Write your name on another sheet of paper. Have a helper forge (copy with the intent to deceive) your signature 1 to 2 inches (2.5 to 5 cm) below your real signature. Make a top-of-the-letter analysis of the two signatures. How do they compare? Could this method of handwriting analysis prove that your helper’s signature was forged?

Explanation

An individual’s handwriting depends on several things, such as the brain, the eye, and the hand of the individual. It is affected by a person’s physical and emotional well-being, the position in which he or she is writing, and circumstances that might influence speed. Normally, a person’s handwriting will be slightly different from signature to signature. So, is a series of signatures on checks are exactly the same, it may indicate that someone forged the signatures by copying or tracing them. If the signatures are very different, however, this can also indicate that the signatures are fakes.

A signature in often all that is needed to withdraw money from a bank account, to write a check, or to make a purchase with a credit card. These are most common situations in which forgery, the act of falsifying documents, occurs. Every year, millions of dollars are lost to forgeries. Forgeries are found by comparing the signature in question with a known example of a person’s handwriting. For example, banks and credit card companies keep a file of copies of their customer’s signatures, and if they think that a check or credit slip might be a forgery, they will compare the signature in question with the signature in their files. If the signatures are different, they will call the police for a complete investigation. Forensic scientists will then do an even more thorough analysis of the signatures.

Typewriting Analysis

2008-06-04T16:52:00.000-07:00

If a crime communicates using a typewriter or a computer printer, it may be possible to identify which machine was used. A typed letter demanding blackmail money or instructing someone where to find a kidnapping victim could be traced back to a suspect’s typewriter or compuer printer. Try the following activity to investigate how detectives analyze typewriting to solve crimes.

Materials

- pencil
- paper with typing on it from several sources, such as papers your friends and family members have typed using different typewriters and computers
- scissors
- glue
- 3-by-5-inch (7.5-by-12.5-cm) index cards
- magnifying lens

Procedure

1. Use the pencil to number all of the typed pages yopu’ve collected.
2. Use the scissors to cut several words out of each page. Glue the words on the index cards, using a separate card for words taken from each page.
3. Record the number of the page the words came from on each card.
4. Use the magnifying lens to obeserve the words on each card. What do you notice about each? Compare the same letter, such as e or a, on each card. How are the letters different?

More Fun Stuff to Do

Have a helper cut a word from one of the pages while you look away. Try to determine which page the word came from by comparing it to your sample cards.

Explanation

Few people write letters on typewriters today. Word processors, computers, and printers have made writing letters much easier. Even so, there are differences between how a letter is made by each machine. By looking carefully at those differences, detectives can determine which machine wrote a certain letter.

Detective Science in Action

In a famous spy case in 1950, Alger Hiss was brought to trial for passing secret documents to the Soviet Union. Hiss was convicted of perjury (lying while under oath), largely because of the evidence that involved his typwewriter. Typed documents taken from a Soviet spy contained valuable information from the U.S. Styate Department. The typing on these documents matched Hiss’s typewriter, which had rather unusual print. The prosecution claimed that Hiss had used the typewriter to copy State Department documents that were later given to secret agents from the Soviet Union.

Indented Paper

2008-06-04T16:50:00.000-07:00

If another piece of paper is directly under the piece that is written on, the paper underneath will pick up an impression of the writing. This can be valuable evidence for a detective who is looking for clues in a missing-person case or trying to match the origin of a ransom note in a kidnapping case. Try the following activity to see how this technique is done.

Materials

- several sheets of white paper
- ballpoint pen
- lamp or other light source
- pencil

Procedure

1. Stack the paper. Use the ballpoint pen to write an address or a phone number on the top sheet of paper.
2. Remove the top sheet, then hold the second sheet of paper up to the lamp. Can you see anything?
3. Lay the second sheet flat. Use the edge of the pencil lead to lightly shade over the place where the writing was made. Can you read the address or phone number on the second sheet?

More Fun Stuff to Do

Repeat the experiment, using different types and amounts of paper, and exerting either more or less pressure while writing. Do these changes affect your ability to read the writing on the second sheet of paper?

Explanation

How well the impression can be read will depend on a number of factors, such as the thickness of the paper, whether the sheets were on a hard or a soft surface, and the amount of pressure exerted by the writer.

If an indented sheet is found as evidence at a crime scene, this technique can be used to match it to a threating letter or a ransom note. If a diary or a business ledger with pages torn out is found, this technique can also be used to determine what was written on the missing pages.

Decomposition

2008-06-04T16:46:00.000-07:00

Decomposition is the natural pprocess of decay. Often the decompositon of materials surrounding a body can give a forensic scientist valuable information. Not all materials decompose at the same rate. Organic material, which is material from plants or animals, decomposes differently from inorganic, or man-made, material. Forensic scientists can study the state of decomposition of these materials to approximate time of death. Try this activity to learn materials can decompose at different rates and how that information can help solve crimes.

Materials

- clear plastic 2-qurt (2-liter) soda bottle
- scissors
- cheesecloth
- rubber band
- tape
- 2 cup (500 ml) sand
- 2 quarts (2 liters) garden soil (from an outdoor location)
- organic material, such as leaves, twigs, grass, shredded newspaper, and needles
- inorganic materials, such as Styrofoam, plastic, and scraps of fabric or leather
- pen or pencil
- notebook
- rubber gloves
- several sheets of newspaper
- stick
- worms (optional)
- tap water
- adult helper

Procedure

NOTE: This activity requires adult help.

1. Remove the label as best you can from the plastic soda bottle.
2. Have your adult helper cut the bottle into two sections, making the cut approximately one-third of the way from the bottom.
3. Cover the mouth of the bottle with cheesecloth and secure it with the rubber band.
4. Turn the drop section of thebottle upside down and place it in the bottom section as shown. Tape the two sections together.
5. Put the sand in the upside-down container. Place a 1-cup (250 ml) layer of the garden soil on top of the sand.
6. Look at the organic and inorganic materials. Which items do you think will decompose quickly? Why? Whicj items do you think will take longer to decompose? Why? Record your predictions in your notebook.
7. Add a small amount of each organic and inorganic materialto the container, then add another layer of soil. Continue to layer organic and inorganic materials and soil until they reach the top of the container. Add more materials on top of the last layer of soil.
8. Add worms to the container, if you like.
9. Pour water into the container until it starts to drip through the cheesecloth.
10. Set the container where it will not be disturbed for a month. Water the container twice a week.
11. Observe the container every other day. Record your observations.
12. After a month, put on the rubber gloves and pour the contents of the container onto the newspaper. Use the stuck to move the soil arround. Observe the condition of the organic and inorganic materials. Were your prediction correct?

CAUTION: Always wear rubber gloves when examining the experiment materials. Return worms to the earth and throw out the rest of the project when you are finished. Be sure to wash your hands thoroughly when you are done.

Explanation

Decomposition is nature’s way to recycle organic, or living, material. Organic material is broken down into nutrients that can be reused by plants as they grow. Some inorganic, or nonliving, material is broken down as well, but usually at a slower rate. Bacteria, fungi, worms, and microorganisms all help to break down these materials.

Worm in particular help to speed up the process of decomposition. They make extensive networks of tunnels that help air and water reach the roots of plants. The tunnels also provide air and water for other soil-dwelling insects and small organisms that help with the process of decomposition. Worms also turn the soil by moving deep soil up to the surface and by dragging plant materials underground. One cup (250 ml) of soil may contain more than 5 billion living creatures!

Forensic scientists use their knowledge of the decomposition rates of various substances to help solve crimes in several ways. For example, the state of decomposition of a letter found behind a house could link a suspect to the time of robbery, while a rotting apple core could be an important clue for police looking for a lost camper.

Heat Loss

2008-06-04T16:40:00.000-07:00

There are many timesthat the temperature of an object plays an important role in solving a crime. Heat from the engine of an automobile may indicate that it has just been driven. A warm cup of coffee on a kitchen table may mean that a suspect has just left. The temperature of a body can indicate to detectives when a death has occurred. Try the following activity to see how temperature can be used by forensic scientists.

Materials

- 2 cup (500 ml) of hot coffee
- coffee cup
- thermometer (measures up to 212oF [100oC])
- stopwatch or watch with second hand
- pen or pencil
- notebook
- adult helper

Procedure

NOTE: This activity requires adult help. Have your adult helper keep the hot coffee at the same temperature throughout the experiment by placing it on a stove or hot plate.

1. Have your adult helper pour 1 cup (250 ml) of hot coffee into the coffee cup.
2. Put the thermometer in the coffee, start your stopwatch, and record the temperature of the coffee in your notebook.
3. Continue to record the temperature of the coffee at 1-minute intervals until the temperature no longer changes. Empty the cup of coffee.
4. Leave the room. Have the adult helper pour another cup of hot coffee into the coffee cup and note the time that he or she pours the coffee.
5. Have the adult helper wait several minutes before inviting you back into the room.
6. Take the temperature of the coffee. Compare the temperature to your records. How many minutes has it been since your helper poured the coffee into the cup?

Explanation

When the object is removed from a source of heat, its temperature begins to drop. It cools rather rapidly until it reaches the temperature of the surrounding air, at which point its temperature stabilizes. The heat loss of the same size of object at the same initial temperature occurs at the same rate each time. This allows one to determine, with some degree of accuracy, the time that the object was removed from the heat source. In this activity, as long as the same amount of coffee at the same initial temperature was poured the second time, and as long as the room temperature did not change, you should have been able to estimate the time the coffee was poured.

At death, a body stops generating heat and its temperature drops gradually. At first the cooling is relatively rapid –approximately 1.5oF (0.8oC) per hour—but this rate slows after a few hours. In addition to size, initial temperature, and the temperature of the surroundings, body type will also affect the cooling rate. A thin body will cool more rapidly than a heavier one. By taking a body’s temp[erature, a forensic scientist can estimate the time of death.

Microorganism

2008-06-04T01:48:00.000-07:00

Very small plants and animals called microorganisms are found on land and in the water. Like microbes, seeds, and spores, microorganisms can be important in an investigation. Try the following activity to investigate microorganisms that are found in water.

Materials

- large glass jar with lid
- water from a pond or lake
- magnifying lens
- microscope (optional)

Procedure

NOTE: This is an outdoor activity

1. Use the jar to collect some water from a pond or lake, then put the lid on the jar.
2. At home, use the magnifying lens or microscope to examine the water for microorganisms. How many different microorganisms can you find?
NOTE: Many of the microorganisms are clear or light-colored and are very small, so you will have to look carefully. They may appear to be small that move!

Explanation

Small plants and animals live in the water are the foundation of all life. These microorganisms are eaten by larger organisms, which in turn are eaten by still larger organisms. This food chain allows many different organisms to live on earth.

Microorganisms found in the water can give valuable information to a detective. Microorganisms called diatoms (microscopic algae that contain a sandlike substance called silica in their cell walls) are very important. The presence or absence of diatoms in a dead body found in water can tell forensic scientists whether the victim drowned or died before entering the water. When death is caused by drowning in natural water, such as lakes and rivers, the water in the body, aspecially that in the lungs but even water in the bloodstream, will contain diatoms. If the victim was already dead when the body entered the water, no diatoms will be found.

In investigations in which a body is found in a different location from where it drowned, forensic scientists study diatoms to determine with considerable accuracy the area of origin. This is because there are over 15,000 species of diatoms, and any combination of them found in a sample is like to be unique.

Dust and Dirt

2008-06-02T18:32:00.001-07:00

Dust, dirt, and soil can be important evidence in an investigation. Try the following activity to see how dirt can be used to solve a crime.

Materials

- dirt from three location
- plastic bags
- marking pen
- 3 sheet of white paper
- magnifying lens

Procedure

NOTE: This is an outdoor activity.

1. Collect dirt from three locations. Place it in the plastic bags and mark the location on each bag.
2. At home, place a dirt sample from each bag on separate sheets of white paper. Examine the samples with the magnifying lens.
3. How are the dirt samples different? Is the soil light or dark? What does the soil look like? What size are the gains in the soil? Do you see any stones? Is there any decaying plant material in the soil? What characteristics could you use identify the dirt from a particular place?

Explanation

Soil is one-half air and water, both of which are necessary for plants and animals to live. The rest of soil consists of recycling organisms-such as fungi, molds, bacteria, and earthworms- pieces of rock, and humus (decaying plant and animal matter). The size of the soil particles determines whether soil is sand, silt, or clay. Sands has the largest soil particles and clay has the smallest.

All this information can be used to study soil samples found at a crime scene. Dust and dirt are common as trace evidence because they are easily carried from the scene of a crime in the soles of shoes, on clothing, or on the tires of a vehicle. Forensic scientists compare the dust and dirt found at a crime scene with selected samples to determine where they came from.

Detective Science in Action

In 1977, Janie Sheperd had been missing for four days. Her car, discovered on a London street, had been driven roughly 75 miles (120 km) from her home. By analyzing thick deposits of mud found undermeath the vehicle, investigators determined that the car had been driven in one of four surrounding counties, which greatly narrowed the search area.

Seed and Spores

2008-06-01T21:29:00.000-07:00

Small seeds found on the suspect’s clothes or in a vehicle driven by the suspect can be important clues to where that person has been. Try following activity to see how this type of information is used to solve crimes.

Materials

- a pair of old wool socks
- field with weeds or bushes
- white paper
- magnifying lens

Procedure

NOTE: This is an outdoor activity

1. Put the wool socks on over your shoes and walk around the field.
2. Remove the socks and observe them. You should find many seeds stuck to the socks.
3. At home, pick off the seeds from the socks and put them on the white paper. Observe the seeds with the magnifying lens. How many different types of seeds did you collect?
4. Group the seeds so that similar ones are together. Can you guess which plants the seeds came from?

More Fun Stuff to Do

Plant the seeds you collected to see what kind of plants will sprout. To make sure the seeds will sprout, before planting them place them in a plastic bag in the refrigerator for a week. (Most seeds in the wild are used to going through a cold winter before sprouting). You can either remove the seeds from the socks and plat them in a pot filled with soil or fill the socks with soil, water them, and place the soil-filled socks on an old plate. Create your own Chia socks!

Repeat the original activity in a different field with different socks. Compare the seeds found in each field. How are they different? Can you tell by looking at the seeds found on the socks which field they came from?

Repeat the original activity in a different season of the year. Compare the seeds found in each season. How are they different?

Explanation

The kinds of plants that grow in a particular area determined by several factors, such as soil type, amount of water, and temperature. Most plants go through a growth cycle each year. In the spring, the plants sprout, begin growing, and then bloom, or flower. They continue to grow rapidly in the summer. In the autumn, the plants get ready for their quiet period.

Grasses and many weeds release seeds into the air or onto the ground in the preparation for the next spring. During the winter, the plants are dormant, meaning that they are alive but asleep. In the spring, seeds will sprout and the cycle begins again.

Seeds come from complex plants like grasses, bushes, and trees. Simple plants like bacteria, algae, mosses, and ferns produces spores, which are small cells that can develop into a new individual.

Using seeds and spores can be an effective way to help identify where a suspect has been walking and to link him or her to the scene of a crime. For example, if seeds found stuck to a suspect’s socks match seeds from grasses near a warehouse robbery, the evidence shows that suspect had the opportunity to commit the crime.

Microbes

2008-06-01T21:27:00.000-07:00

Our body carry organisms that are too small to see. These creatures, called microbes, can be used to identify whether a suspect wore certain clothing or whether he or she was at the scene of a crime.

Materials

- ½ cup (125 ml) tap water
- saucepan
- 4 packages of unflavored gelatin
- timer
- clean 1-quart (1-liter) jar with lid
- trash can
- tennis shoes
- cotton swab
- rubber gloves
- dishwashing liquid
- adult helper

Procedure

NOTE: This is an outdoor activity and requires adult help.

1. Have your adult helper prepare the gelatin by boiling water in the saucepan and dissolving the gelatin packages in the boiling water.
2. Allow the gelatin to cool until it is enough to handle but not solid (about 5 minutes).
3. When the gelatin has cooled, pour it into the jar.
4. Hold the jar over the trash can. Tip the jar on its side and let the excess gelatin pour out.
5. Set the jar on its side and leave it undisturbed for 4 hours.
6. Put the tennis shoes on without socks and go play outside for at least 30 minutes.
7. Remove the shoes. Take the cotton swab and rub it between all your toes.
8. Reach into the jar and carefully brush the gelatin with the cotton swab so that you makle a wavy line in the gelatin as shown.
9. Wash your hands and feet.
10. Place the lid on the jar and put the jar in a warm, dark location. Leave it there for 4 days.
11. After 4 days, observe the gelatin in the jar. What do you see?
CAUTION: Do not touch the gelatin! Don’t keep the jar longer than four days.
12. When you are done with the experiment, put on the rubber gloves, fill the jar with hot water, let it soak for 5 minutes, and then wash the jar. The gelatin will dissolve and can be washed down the sink.
CAUTION: Be sure to wash your hands thoroughly when you are finished.

Explanation

The side of your shoes is warm, dark, and damp from sweat. This is a perfect environment for microbes to grow, as they like warm, dark, damp places. Your jar had a similar environment. The gelatin provided food for the microbes that were on your feet. Having food and a nice place to live allowed the microbes to eat and reproduce.

After four days, you should have been able to see grooves in the gelatin where the microbes had eaten it. Sometimes you might have seen different colors, depending on the type of microbe that was living on your feet and on the gelatin. If you could look at microbes under a microscope, you would see that they have unique characteristics, such as size, shape, color, and reaction to certain chemicals.

Microbes can be found not only on the inside of shoes, but on the soles of shoes and your skin as well. Forensic scientists compare microbes found at a crime scene to known microbes and to those found on a suspect. If the microbes match, they can be used to place the suspect at the crime scene.

DNA Testing

2008-06-01T21:24:00.000-07:00

If cells, such as blood cells, are found at the scene of a crime, forensic scientists can perform a test called DNA profiling to attempt to link the cells to a certain suspect. DNA profiling is one of the most important discoveries in recent scientific history. DNA profiles look similar to the bar codes found on the products we buy. Try the following activity to simulate how DNA profiles are compared.

Materials

Bar code shown

Procedure
1. Observe the bar codes shown.
2. Match the mystery bar code to bar code A through D.

Explanation

The mystery bar code is identical to bar code C. Just as bar code contain information about the identification of a product, DNA profiles contain coded information about the make up of a human being. DNA (deoxyribonucleid acid) is a basically the blueprint or recipe for the human body. DNA is located in the nucleus (center) of every human cell. Every cell in the human body has 46 chromosomes, which contain coded information arranged into groups called genes. This coded information is a person’s DNA. Each person’s is unique, so only very small samples are required for analysis.

DNA analysis, which can be doen by the crime lab or an independent laboratory, is a complicated procedure. It involves the following steps:

1. DNA is removed from the cell nucleus.
2. The DNA strands are separated from the rest of the cell parts and chopped into smaller pieces.
3. The human DNA pieces are combined with radioactive DNA. This allows the forensic scientist to track the pieces of human DNA later.
4. The DNA pieces are separated from one another into bands according to size, using gel electrophoresis, a process similar to chromatography. (See project Ink Identification, for more information about chromatography).
5. X-rays are taken of the separated DNA pieces (the radioactive DNA will be easily seen on the X-ray) to record the individual’s DNA profile.

Just as you compared bar codes, forensic scientists can compare a DNA profile obtained from cells found at a crime scene to the DNA profile of a known suspect, to determine whether the suspect was at the scene of the crime. Examples of DNA profiles are shown.

We hear in the news about forensic experts performing DNA tests in spectacular court cases. However, the greatest number of DNA tests are routinely conducted to establish the identity of a father or a child, or to prove or disprove family relationships in immigration applications.

Feet and Inches

2008-06-01T21:19:00.000-07:00

Even the bones of the feet can tell you a lot about the person they came from. Try the following investigation to see what feet reveal about a person’s height.

Materials

- tape measure
- pen or pencil
- paper
- calculator
- several helpers

Procedure

NOTE: This activity works if the helpers are older people who have stopped growing, rather than young children.

1. Have each helper remove his or her shoes. Use the tape measure to measure the height of each helper in inches (cm). Write each person’s name and height on the paper.
2. Have each helper stand with his or her left heel against the wall and perpendicular to the wall.
3. Carefully measure the length in inches (cm) of each person’s left foot, from the wall to the big toe. Write that information next to each person’s name and height.
4. Look at the numbers. Do you notice a pattern?
5. Use the calculator to divide the length of each person’s left foot by his or her height. Multiply the result by 100. What result do you get?

More Fun Stuff to Do

Have a helper stretch his or her arms out sideways as far as they can go. Measure the distance from the tip of the middle finger on one hand to the tip of the middle finger on the other. Compare that measurement to your helper’s height. What do you notice?

Explanation

The results of your calculation in step 5 should all have been approximately 15. For example, if a person is 63 inches (160 cm) tall and his or her left foot is 9 ½ inches (24 cm) long, the result would be 9 ½ inches (24 cm) divided by 63 inches (160 cm) times 100 equals 15. This means that the length of a person’s foot is about 15 percent of his or her height.

If a forensic scientist had to identify a person using only the bones of the foot, he or she could approximate the height of that individual using this technique. This is because the bones in the body grow at certain rates and are in proportion to one another.

Thus, in the More Stuff to Do section, the distance between the tips of the middle fingers when the arms are out stretched is the same as a person’s height. As a person’s grows taller, the feet grow bigger and the arms grow longer at the same time. By the time he or she is full grown, foot length and arm span will give approximate values for height.
These values are not always true as people grow. The ratio of one body part to another will change greatly throughout childhood. For example, the circumference of the head of a newborn, is about 25 percent of the baby’s height, while that of an adult is only about half that value.

Bone Identification

2008-06-01T21:17:00.000-07:00

Bones can tell a great deal about the life of people who died. They can give hints about their ancestry, sex, age, and stature (height), and often they help identify someone. Bones in a criminal investigation can give clues about the time and manner of death. Try the following activities to learn more about bones and what they can tell you.

Materials

- 2 stockpots, one with lid
- tap water
- whole chicken
- timer
- tongs
- platter
- ½ cup (125 ml) baking soda
- scrub brush
- adult helper

Procedure
NOTE: This activity requires adult helper.

1. Fill one stockpot halfway with water. Put the chicken in the pot and cover it with the lid.
2. Have your adult helper set the pot on the stove burner, set the heat to medium, and boil the chicken for 2 hours.
3. Have your adult helper use the tongs to transfer the chicken from the pot to the platter. Let the chicken cool. When the chicken is cool, remove as much meat from the bones as possible.
NOTE: Have your adult helper save the good parts of the meat for a meal.
4. Fill the second pot halfway with water. Add the bones and the baking soda.
5. Ask your adult helper to boil the bones for 1 hour. This should remove all remaining meat from the bones.
6. Allow the water to cool, then transfer the bones to the platter. Use the scrub brush to clean the bones.
7. Examine the bones. How are they like? How are they different? If you were given only ane bone from the chicken, would you know where in the chicken it came from?
8. Use the diagram to help you reconstruct the chicken skeleton.

Explanation

Forensic anthropologists study the bones of the dead. They use the same techniques and discoveries to help solve twentieth century crimes as other anthropologists use to unveil the secrets of ancient civilization. Indeed, many of the nation’s forensic anthropologists spend much of their time digging into remains of ancient times.

One the first things that forensic anthropologist must determine is whether a bone is human or animal. This is often more difficult than it sounds. Some other mammals have bone very similar to human bones. For example, the bones in a bear paw look almost exactly like the bones in the human hand. Investigators also need to know whether bones are recent or ancient. This will help them determine whether the bone comes from a place of historical significance or the scene of a crime.

The skull can be used to help re-create what a person looked like. Forensic sculptors use computers to help put flesh and skin on a skeleton and thus match a skull to a photograph of a missing person. These techniques have been used to give other anthropologists an idea of what dinosaurs looked like.

The skeleton can give many important details about a person, including his or her occupation. For example, the bones of waiters and tennis players show signs of arm strength, with greater development on their strong side. Male pelvic bones (the bones that from the hips) are different from those of the female. Men’s pelvic bones are narrow and steep while women’s are shallower and broader. Forensic anthropologists often use the features of the eye sockets and nose cavity to categorize people in one or more continental or ancestral groups.

One of the best collaborative efforts in the science world is that between the Smithsonian Institution’s Department of Anthropology and the FBI in Washington D.C. Here, pure science and hard-nose police work team up to help solve some of the most tantalizing of humanity’s past and present.

Teeth Impressions

2008-05-30T00:39:00.000-07:00

Teeth and teeth impressions can be used in an investigation to identify an unknown person and to learn information about him or her. Try the following activity to learn more about what teeth can tell you.

Materials

- scissors
- Styrofoam plate
- Marking pen

Procedure

1. Cut the Styrofoam plate into six equal wedges.
2. Stack two of wedges together, and cut 1 inch (2.5 cm) from the pointed end of both. Throw away the pieces that you cut off.
3. Slip the cut ends of the two wedges into your mouth. Push them in as far as possible while still being comfortable.
4. Bite down on the wedges firmly, then remove them.
5. Label the top wedge Impression of the Top Teeth and the bottom wedge Impression of the Bottom Teeth.
6. Examine the teeth impressions. How many teeth made marks in the top impressions? How many made marks in the bottom impressions? What features of the impressions are useful in telling the top teeth from the bottom teeth? How are the teeth different?

More Fun Stuff to Do

Collect teeth impressions from several helpers. Be sure to label each impression with the person’s name whether it is the top or bottom teeth. Leave the room, then have one helper take a bite from a piece of cheese or hard chocolate. Can you identify who took the bite by comparing the impression in the cheese or chocolate to the set of impressions?

Explanation

Humans are provided with two sets of teeth, which appear at different times in life. The first set, called deciduous teeth, appear when we are children. The second and final set, the permanent teeth, appear later and replace the deciduous teeth.

This process of replacement begins at about age six, when we lose our front incisor teeth, and continues to about age eighteen, when we get our third set molars, commonly called our wisdom teeth. We have twenty deciduous teeth: four incisors and two canines (which cut or tear food) and four molars (which chew and grind food) in each jaw. We have thirty-two permanent teeth: four incisors, two canines, four premolars, and six in each jaw.
The arrangement of each person’s teeth is unique and can be easily used to help identify a person. The number and type of teeth are valuable in determining the age of the individual. Forensic dentists can compare teeth impressions to dental records. Eighty percent of time, teeth impressions are used to identify unknown victims.

Detective Science in Action

Teeth impressions have used to identify many criminals. One hungry burglar was caught because of a half-eaten piece of cheese he left at the scene of the crime. The burglar became hungry during a break-in and took a piece of cheese out of the refrigerator. He had just taken one bite from the cheese when he heard a noise. Startled, be dropped the cheese and ran out of the house. When police arrived, they found the cheese. They matched the teeth impressions of the suspect to the bite marks in the cheese.

Ballistics

2008-05-21T18:12:00.001-07:00

A gun leaves an impression on the bullets that are shot from it. Forensic scientists can use these impressions to match bullets to the type of gun used. The field of science that studies bullets and other shot objects is called ballistics. Try the following activity to investigate how detectives can solve a crime by using their knowledge of ballistics to match bullets to a gun.

Materials
Ballistic evidence shown in the drawing

Procedure

1. Using the ballistic evidence shown, match the bullet found at the scene of a bank robbery with the sample bullets fired from several guns.
2. Which type of gun was used in the crime?

Explanation

The first thing that a forensic scientist will determine when examining a bullet is its caliber. A bullet’s caliber is the same as its diameter, the length of a straight line through the center of the flat end of the bullet. The diameter of a bullet is measured in either inches or millimeters. A bullet that is 0.22 inches in diameter is a .22-caliber bullet. It is used in .22-caliber rifle, which has a barrel 0.22 inches in diameter. Similarly, a 9-mm pistol uses a bullet that is 9 millimeters in diameter. Forensic scientists will compare the caliber of a bullet found at the scene of a crime to the caliber of a gun found on a suspect. But that is just the beginning of their ballistic analysis.

As early as the sixteenth century, gunsmiths were improving the speed and accuracy of guns by cutting grooves called rifling grooves around the insides of guns barrels. These grooves make the bullet spin down the barrel and in the air, thus increasing the speed and force of the bullet. Bullets are made slightly larger than the gun barrel to ensure a tight fit, which results in the characteristic rifling marks on the bullet after it has been fired.

Inside the gun barrel, the rifling grooves and the lands (the area inside the gun barrel that remains after the barrel has been grooved) create a distinctive pattern that does not change, so any bullet that passes through the barrel of a particular gun will bear the rifling marks of the gun. In addition to rifling marks made on the bullet, identifying marks are made on the cartridge (the cylindrical container of the bullet, which holds the gunpowder and stays in the gun when it is fired). These marks are caused by the firing pin (the piece of metal that strikes the cartridge and ignites the gunpowder).

Matching bullets to guns is one of the simplest procedures in forensic science. By the knowing the caliber of a bullet and the land and groove configuration, a forensic scientist can tell detectives what type of gun the bullet came from.

Detective Science in Action

Forensic evidence proves a person’s innocence as often as it proves a person’s guilt. Recently, for example, a prospector in Alaska was found in his remote cabin dead from a gunshot wound. The immediate suspect was the prospector’s partner. Indeed, when the police found the partner, he was carrying a recently fired rifle and had blood on his boots.

A hundred years ago, the partner would have been found guilty based on those two bits of evidence alone. But forensic evidence showed that the bullet that killed the prospector came from a pistol, not the partner’s rifle, and that the blood on the partner’s boots came from a recently killed deer.

Glass Fragments

2008-05-18T21:07:00.002-07:00

Glass fragments are one the most frequently found substances at crime scenes: Criminals break windows to gain entry into buildings, hit-and-run accidents result in broken glass, and so on. Try the following activity to see how forensic scientists analyze glass fragments at a crime lab.

Materials

- jigsaw puzzle

CAUTION: Do not try this activity with actual glass fragments.

Procedure

1. Dump the jigsaw puzzle pieces onto a table or floor. Turn each piece facedown.
2. Assemble the puzzle using only the shape of the pieces as a clue, not the elements of the picture.
3. Did you find this easier or more difficult than usual?

Explanation

Forensic scientists at a crime lab use a technique called the jigsaw method to analyze glass fragments. The jigsaw method works because when glass breaks, its surface fractures unevenly. This breaking process produces unique shapes of glass that will lock only into the pieces that were next to them at the point when the glass broke, just as each piece of a jigsaw puzzle will lock only into the pieces that go next to it.

Forensic scientists use the jigsaw method of glass-fragment analysis to solve crimes. For example, investigators may wants to know whether a piece of glass found in a hit-and –run victim’s clothing matches the glass from a broken headlight of a suspect’s automobile.

As you saw in this activity, the jigsaw method is very difficult. Forensic scientists perform other tests to match glass fragments to the scene of a crime.

Tool Impressions

2008-05-18T21:07:00.001-07:00

The soda machine at your school has been broken into and the money has been taken. Hall monitors stops two students from another school in the hallway and fined a crowbar in one student’s backpack. How can your school prove that these students committed the crime? Try the following activity to investigate how detectives can match tools to the scene of a crime.

Materials

- hammer
- 16d nail (about 3 inches [7.5 cm] long)
- scrap piece of plywood
- pliers
- crowbar
- screwdriver
- timer
- adult helper

Procedure

NOTE: This activity requires adult help.

1. Have your adult helper use the hammer to pound the nail into the plywood so that ½ inch (1.25 cm) of the tip of the nail sticks out the back of the wood.
2. Leave the hammer, pliers, crowbar, and screwdriver near the plywood.
3. Tell your helper that he or she will have 3 minutes to remove the nail from the board, using several of the tools that are supplied.
4. Leave the room and time your helper for 3 minutes while he or she performs the task. Do not watch while your helper removes the nail.
5. When 3 minutes are up, try to match the marks made on the wood with the tools that were used. Which ones are easy to match? How could police use this information to investigate crimes?

Explanation

Almost any device used to perform work can be called a tool, and almost every tool will leave behind some mark of its use. There are three categories of tool marks: impression, such as those made by a hammer or a crowbar in a soft surface; cut marks, such as those made by wire cutters, saws, and the like on material; and scratch marks, such as those made by a knife blade scraping over a surface. Like other forms of trace about which tools were used at a crime scene. If the tools found on a suspect match the tool marks left at the scene of a crime, police have evidence to link the suspect to the crime.

One of the most frequently found tool impressions is the ‘jimmy’ mark found at the site of a break-in or forced entry. These marks occur when a criminal wedges a jimmy--a crowbar, screwdriver, or tire iron--between a door and its jamb, or between a window and its still, and exerts pressure until the door or window opens. The hard metal of the tool compresses the wood, leaving an impression of the tool in the wood.

Casts

2008-05-18T21:06:00.001-07:00

Footprints, shoe prints, and tire tracks found at the scene of a crime can be important evidence to connect a suspect with a crime. A forensic scientist makes a cast (a form made by pouring plaster of Paris into a mold) of this type of impression. Try the following activity and learn how to make a cast of a shoe print.

Materials

- tape
- 2 pieces of 1-by-10-inch (2.5-by25-cm) cardboard
- 2 pieces of 1-by-5-inch (2.5-by-12.5-cm) cardboard
- petroleum jelly
- shoes
- soft soil in an outdoor area
- plaster of Paris
- water
- paper cup
- craft stick
- timer
- newspaper
- small paintbrush

Procedure

NOTE: This is an outdoor activity

1. Tape the four pieces of cardboard together to make a 5-by-10-inch (12.5-by-25-cm) rectangular frame. Grease the inside of the cardboard frame with petroleum jelly.
2. Wearing the shoes, press the sole of one show into soft soil so that you leave a shoe print in the soil.
3. Surround the shoe print with the cardboard frame.
4. Mix plaster of Paris with water in the paper cup according to the instructions on the box of plaster. Stir with the craft stick.
NOTE: Be sure to mix the plaster in throwaway container. Do not pour plaster down the sink, as it can clog the drain.
5. Pour the liquid plaster over the print. Allow it to dry for 1 hour.
6. Lift the plaster cast out of the ground. The soil will stick to the plaster. Bring the plaster cast indoors and place it on newspaper. Allow the plaster to dry overnight.
7. Brush the loose soil from the cast with the paintbrush.
8. Observe the cast. What can you tell about the shoe that made the print?

More Fun Stuff to Do

Make shoe-print casts of several helpers. Can you identify which shoes made each print? Make a cast of the track made by a tire in mud. What can you tell about the tire by looking at the cast?
Explanation

Casts of impressions, such as shoe prints, tire prints, or even bare footprints, taken at the scene of a crime can connect a person or vehicle with the crime.

When a shoe makes an impression in soft material, such as soil, it leaves behind a negative mold of itself, including any special marks or a logo or tread pattern, may be visible. By carefully filling the mold with the plaster of Paris, investigators can make an exact reproduction of surface of the sole of the shoe.

This reproduction is then sent to the crime lab where forensic scientists analyze it and compare it to known objects. For example, the pattern on the sole of a running shoe can be used to identify the brand of shoe, or the wear pattern may indicate that the wearer walks with a limp or drags one foot. Similar marking on a tire cast can tell forensic scientists what of tire made the mark, and may even tell what type of car the tire were on.

Paper Fibers

2008-05-18T21:05:00.000-07:00

A detective investigating a crime looks for any material that might connect a suspect with the crime scene. A burned match found in an ashtray can provide evidence that links a suspect to the crime. Try the following activity to see how the paper fibers of a torn match can help forensic scientists solve a crime.

Materials

- 3 identical unused matchbooks
- magnifying lens
- paper
- pencil

Procedure

CAUTION: Do not light matches during this activity.
1. Tear match out of each matchbook.
2. Use the magnifying lens to examine the torn end of each match.
3. Draw a sketch of the torn end of each match. Do you see any special features that would help you link the match to the matchbook from which it was torn?
4. Use the magnifying lens to examine each matchbook. Carefully examine where each match was removed from the matchbook. Can you find any evidence on the matchbook that would help you link the torn match to it?

More Fun Stuff to Do

While you are out of the room, have a helper remove a match from each matchbook. Can you link each match to the matchbook from which it was torn?

Explanation

Paper is made of various wood fibers that have been pressed together. These are randomly arranged in the paper and can be of various lengths. When you tear paper, the fibers separate. Since no two pieces of paper have fibers that are identical in arrangement and length, all paper tears differently. Even if you tried, you could not make identical tears in two pieces of paper.

Matches in a matchbook are made of paper. The end of a paper match torn from a matchbook is distinctive and can be used to match it to the matchbook from which it was torn. If a match torn from a matchbook is found at a crime scene and can be linked to a matchbook found on a suspect, this evidence could prove that the suspect was at the scene of the crime.

Cloth Fibers

2008-05-18T21:04:00.002-07:00

Like hair, cloth fibers are among the most common items left as trace evidence at a crime scene. Forensic scientists analyze, identify, and compare cloth fibers to place a suspect at a crime scene. For example, wool thread caught on a window frame at a crime scene may match the sweater found at a suspect’s house. Try the following activity to see how fibers can be used as evidence in an investigation.

Materials

- several different fabrics, including some with natural fibers, such as cotton and wool, and some with synthetic fibers, such as nylon or crayon
- transparent tape
- several sheets of white paper
- marking pen
- magnifying lens
- microscope (optional)
- pen and pencils
- notebook

NOTE: If you used old clothing, be sure to ask adult permission first, or ask at your local fabric store for fabric remnants.

Procedure

1. Pull fibers from several fabrics.
2. Tape each fiber to a separate sheet of white paper. With the marking pen, label the fiber according to which fabric it is from and how it was obtained.
3. Examine each fiber with the magnifying lens and microscope, if available. Record your observations in your notebook.

More Funs Stuff to Do

Ask a helper to pull a fiber from one of the fabrics without telling you which fabric it’s from. Using your labeled samples and magnifying lens or microscope, can you identify what the fiber is and which fabric it came from?

Explanation

There are four sources of fibers: animal, vegetable, mineral, and synthetic. The most common animal fibers are wool, cashmere, and silk. The most common vegetable fiber is cotton. Asbestos is the only mineral fiber. Synthetic fibers make up about 75 percent of all textile fibers in the United States and are the most common fiber investigated in the crime lab. There are over 1,000 different types of synthetic fiber, classified by their chemical composition, fiber shape and size, additives, and manufacturing process.

Like hair, fibers are important trace evidence. A forensic scientist use a vacuum cleaner to collect fibers, hairs, and dirt found at the scene of crime. These materials are then taken to the crime lab to be analyzed and compared to known samples. Investigators can link a suspect to the scene of a crime by matching fibers found at the scene of a crime to fibers found on a suspect or in a suspect’s vehicle or home.

Hair specimens

2008-05-18T21:04:00.001-07:00

Hair left at a crime scene can be important evidence in a forensic investigation. A strand of hair can indicate the age, sex, and race of the person from which it came. Microscopic examination of hair found at a crime scene can confirm that a suspect was at a scene. Not all hair evidence has to be human hair, for example, cat hair found at the scene of a robbery may match the cat hair found on a suspect’s coat. Try the following activity to see how hair is used as evidence in an investigation.

Materials

- strand of hair from several people or animals
- transparent tape
- several sheets of white paper
- marking pen
- magnifying lens
- microscope (optional)
- pen or pencil
- notebook

Procedure

1. Obtain strands of hair from several people. You can take some from their hairbrushes, or cut or pull with permission, several hairs from each head. Include pet hairs in your investigation, if possible.
2. Tape each strand of hair to a sheet of white paper. With the marking pen, label the hair according to whose it is and how it was obtained.
3. Examine each hair with the magnifying lens and microscope, if available. Record your observations in your notebook.

More Fun Stuff to Do

Ask a helper to choose someone who already gave you a hair sample and obtain another strand of hair from that person. Using your labeled samples and magnifying lens or microscope can you identify this person after comparing all samples?

Explanation

The first step in any laboratory examination of hair evidence is for the crime lab to determine whether it is human hair. This is done by first comparing the hair to known human samples. The next step is to note the features of hair, such as its length, diameter, and color, including the distribution of color (hair may be lighter on one end) and any evidence of dyeing or bleaching.

Hair that has been pulled from the scalp-as opposed to hair that has been cut or broken off, or that has naturally fallen out-will often have tissue sticking to the root (the enlarged part of the strand of hair that grows below the surface of the skin). This tissue can be used to identify the owner of the hair through forensic techniques such as blood factor analysis and DNA testing.

Voice Prints

2008-05-18T21:03:00.001-07:00

If investigators have a recording of voice, they can use voiceprints, just as they use fingerprints, to help identify the person on the recording. A voiceprint is a pattern of wavy lines and whorls produced by a recording of a person’s voice. Voiceprints are as unique as fingerprints. Try the following activity to simulate your voiceprint.

Materials

- glue
- ¼-by-¼ inch (6-by-6-mm) mirror
- speaker with connecting wire (a speaker and connecting wire from an old radio is easiest to use)
- cassette recorder
- wire cutters
- flashlight
- cassette recording of your voice
- adult helper

Procedure

1. Glue the mirror to the speaker, about halfway between the center and the edge of the speaker.
2. Ask your adult helper to connect the speaker to the cassette recorder. This can usually be done by using wire cutters to remove ½ inch (1 cm) of insulation from the free end of the speaker connection on the back of the cassette recorder.
3. Darken the room, and then shine the flashlight onto the mirror. Note where the light reflects off the mirror and shines on the opposite wall.
4. Turn on the cassette recorder and play the tape. What happens to the light’s reflection on the wall?

Explanation

Voiceprints can used to identify a recorded voice. In this activity, the recorded voice creates vibrations that are sent to the speaker. These vibrations are unique to the voice and to the words that are being said. The vibrations cause the speaker and the mirror attached to it to move, which causes the light reflected off the mirror to move in the same direction. If you could mark the path that reflected light traced, you would have a line that similar to a voiceprint. It would be possible to identify who, or what, made the sound.

Forensic scientists use voiceprints to compare recorded voices. They normally have a suspect record a 2 ½ -second speech that uses then ten most common words: a, and, I, is, it, on, the, to, we, and you. They then compare the voiceprint used as evidence in a crime.

Detective Science in Action
The first application of voiceprints occurred in Connecticut, where a voiceprint was used to prove the innocence of suspect. The suspect was a man accused of using a telephone to make threats to a family. The principal victim claimed that the suspect had made the calls, while the suspect protested his innocence. Investigators made tape recordings of both the phone calls and the suspect’s voice. An analysis of the phone calls revealed that they had actually been made by two individuals disguising their voices. The suspect was released and the two guilty persons were arrested.

Tough Fingerprints

2008-05-18T21:02:00.000-07:00

As you learned in Project Dusting Fingerprints, some surfaces are better than others for lifting fingerprints. On certain surfaces, even dusting will not make a latent print visible. However, forensic scientists have discovered new ways to make fingerprints visible on difficult surfaces. Try the following activity to learn how to collect tough fingerprints.

Materials

- jar with a lid or other closable container
- two 3-inch (7.5 cm) squares of aluminum foil
- super glue (or glue that contains cyanoacrylate)
- timer

Procedure

1. Open the jar and set it on its side.
2. Put extra oil on your fingertip by rubbing it alongside your nose or in your hair.
3. Press the oiled fingertip on one square of aluminum foil, and then put the foil in the jar.
4. Squeeze a small amount of Super Glue onto the other foil square. Put the second piece of foil next to the foil in the jar.
5. Close the lid of the jar and wait about 30 minutes.
6. Observe the first piece of aluminum foil, the one your finger touched. What do you see?
CAUTION: Be careful not to get the glue on your hands.

More Fun Stuff to Do

Try this procedure with other materials. Repeat the experiment, substituting the aluminum foil with squares of cardboard, wood, cloth, and other materials that did not work very well in Project Dusting Finger Prints.

Explanation

A fingerprint made on aluminum foil cannot be detected using normal procedures, such as dusting, and has to be treated with chemicals. One such chemical is cyanoacrylate, a chemical used in Super Glue and similar products. In this activity, cyanoacrylate in the glue rises into the air. Trapped in the closed jar, this chemical sticks to the invisible oils in the fingerprint and hardens on them. As more cyanoacrylate particles harden on the fingerprint, it becomes visible and can then be easily identified.

There are other chemicals that can be used to make latent fingerprints visible on certain surfaces. Ninhydrin is a chemical that reacts with sweat and oils in the fingerprint to produce a purple image. It is ideal for lifting fingerprints from paper and some other porous surfaces, like bare wood and plaster. Iodine vapor can bring out fingerprints made on rough, absorbent, light-colored surfaces, such as paper and cloth. The iodine vapor reacts with the oil in the fingerprint and turns the fingerprint brown.

Detective Science in Action

Fingerprints first played a major role in solving a murder in 1902. Joseph Reibel was found dead in his apartment in Paris, France. The detective assigned to the case was Alphonse Bertillon, one of the first detectives to collect and record the physical characteristics of criminals, including their fingerprints. At the crime scene, Bertillon found broken glass from a cabinet and blood on the carpet. It was obvious the intruder had cut himself and unknowingly left behind fingerprints on several pieces of the glass. By comparing the fingerprints on the glass to those of several known criminals, Bertillon was able to match them to the fingerprints on the record card of Henri-Leon Scheffer, a convicted swindler. Scheffer was picked up by the police, and burdened with guilt and remorse, he confesses to crime.

Dusting Fingerprints

2008-05-18T21:01:00.000-07:00

How can detectives identify fingerprints left at the scene of a crime? They must remove the prints and transport them back to the crime lab, where they can compare them to other fingerprints on file. One way to locate fingerprints is by a technique called dusting. The fingerprints are coated with powder, then lifted and taken to the lab for identification. Try the following activity to learn how to dust and lift fingerprints.

Materials

- drinking glass
- cocoa
- small paintbrush
- transparent tape
- 5 sheet of light-colored construction paper

Procedure

Note: You get a better fingerprint when more body oils are present. To do this, rub each finger alongside your nose or through your hair before making each fingerprint.

1. Press one finger at a time on the side of the drinking glass.
2. Sprinkle cocoa on the glass to coat the fingerprints.
3. Very gently brush the powdered area with the small paintbrush. When you’ve brushed off the loose powder, you should see the fingerprints.
4. Lift each print from the glass by placing the sticky side of a piece of transparent tape on the dusted finger print and then carefully lifting the tape from the glass. The dusted fingerprint should stick to the tape.
5. Place each piece of tape on a separate sheet of light-colored construction paper.

More Fun Stuff to Do

Try to use other surface to dust for fingerprints. Put fingerprints on a variety of surface, such as wood, cardboard, aluminum foil, smooth paper, rough surfaces with talcum powder and light surfaces with cocoa.

NOTE: Be careful to avoid breathing in the talcum powder, as it can irritate breathing passages. Place prints made with talcum powder on dark-colored construction paper and prints made with cocoa on light-colored construction paper. Which surfaces allow you to make fingerprints that can be identified using the dusting technique?

Explanation

If a criminal’s hands are covered with dirt, paint, or other substances, his or her fingerprints may be easily seen. These are called visible prints. Other prints may be harder to see and may need treatment with chemicals or dust to make them visible.
The best surface for dusting latent prints is one that is smooth, flat, and firm. Fingerprinting with powders does not work well on a surface that is rough or too flexible.

There are several powders that forensic scientists use to dust for latent fingerprints. Two common powders are (1) vegetable black, a fine carbon powder similar to the pencil scrapings that you used in Project Taking Fingerprints, and the choice for light-colored surfaces, and (2) aluminum powder, a fine white powder used on dark-colored surfaces. Forensic scientists use a fingerprinting powder that contrasts with the color of the surface on which the fingerprint is located. This makes the dusted fingerprints more visible and easier to photograph for evidence.

Forensic scientists also add other chemicals, such as lead, cadmium, copper, and mercury, to fingerprint powders to make them stick better to latent fingerprints. Fluorescent and phosphorescent chemicals can also be added to fingerprint powder to make dusted fingerprints glow in the dark.

Classifying Fingerprints

2008-05-12T22:31:00.000-07:00

As you’ve probably learned in the previous activity, it is difficult to identify fingerprints. They are rather small and contain a lot of detail. To simplify their identification process, forensic scientists use a classification system. Try the following activity and learn to classify fingerprints.

Materials
- magnifying lens
- several sets of fingerprints, your own and those of helpers

Procedure
1. Use the magnifying lens to observe several sets of fingerprints. Do you notice characteristic that any of them share? Can you group the prints into categories to make the identification process easier?
2. Look at the common fingerprint patterns in the diagram. Notice that arch and the loop can have several forms and may bend to the right or the left.
3. Try to match the fingerprints that you have collected to one of the common patterns.

Explanation

There are several ways to classify fingerprints. In this activity, you have tried one of the easiest ways. More complex classification systems break down the common fingerprint pastern into smaller groups. For example, forensic scientists divided arches into plain arches (arches that are rounded) and tented arches (arches that are pointed). Loops can be either radial loops, which loop from the right, or ulnar loops, which loop from the left. Similarly, whorls are classes into several subdivisions.

Even more complex classification systems, such as the Henry System, have been developed to help compare fingerprints. The Henry System use a number system to classify the characteristics of a fingerprint as well as the type of finger and hand from which it came. Investigators match a fingerprint to a person by matching the print’s numbers to others prints with the same numbers, rather than by individually comparing a suspect’s fingerprint to every fingerprint on file.

Fingerprints used to be examined and classified by hand. This was a slow, time-consuming process. Now computers can scan a fingerprint and compare it to huge files that have been collected from many police agencies, such as the FBI. This system, called AFIS (Automatic Fingerprint Identification System), can do the work in a fraction of the time. For example, it takes AFIS only two minutes to complete a fingerprint comparison that used to take years to complete by hand.

There is one limitation to AFIS and all fingerprint identification methods. Although there are cover 250 million people in the United States, there are only about 10 million sets of fingerprints on file in AFIS. If a criminal’s fingerprints are not on file, the system does nor work.

Burned Documents

2008-05-12T01:49:00.000-07:00

Even a notice that has been completely burned can be important evidence in a investigation. Try the following activity to restore and read a burned document.

Materials

- ballpoint pen
- sheet of white paper
- metal pie pen
- matches (to be used only by an adult)
- cookie sheet
- ½ cup (125 ml) glycerin (available from drufstore)
- 1 ½ cup (375 ml) tap water
- spray bottle
- adult helper

Procedure

Note: This activity requires adult help.
1. Write the message “Robbery set for 3:00 p.m. on Thursday” on the white paper.
2. Crumple the paper into the ball and place it in the middle of the pie pan.
3. Have your adult helper use the matches to set the paper on fire.
4. Allow the fire to burn out and cool down. When the burned paper is cool, carefully transfer it to the cookie sheet.
5. Observe the burned paper. Can you still see any of the writing on the paper?
6. Mix the glycerin with the water and place the mixture in the spray bottle.
7. Carefully spray the burned paper with the mixture until the paper is completely wet. Gently unfold the crumpled paper and flatten it on the cookie set. Use more spray if necessary.
8. Observe the pape. Can you now read any of the writing?

Explanation

A document may be burned either by accident or on purpose. Either way, handling a charred or burned document is one of the most difficult tasks a crime lab can face. The documents must be transferred to the crime lab with the utmost care and are often hand delivered in a cotton – or wool- lined box. Once the document is in the lab, the forensic scientist begins the careful process of reading it.

First, the forensic scientist must flatten the burned document without causing it fall apart. The glycerin – and – water solution used in the activity softened the burned paper so that you could flatten it. Forensic scientists used a similar procedure. They float burned sheets in a large tray containing a mixture of glycerin, alcohol, and a chemical called choral hydrate to soften the paper.

Once the document is flattened, the forensic scientist tries to read it. Most ballpoint pen inks contain a small amount of metal in the dyes. These metals are able to survive fire, so anything written with a ballpoint pen can be seen when the paper is flattened. The forensic scientist then photographs the document as evidence.

If the writing on the document is not easily visible, the forensic scientist will sometimes photograph the burned document with special film called infer red film. This film enhances the writing on the document and helps make it more visible.

Ink Identification

2008-05-12T01:08:00.001-07:00

A ransom note is important evidence in a kidnapping investigation. If forensic investigators can identify the pen that wrote the note, they may be able to link the note to suspect. There are several ways to identify the type of pen used to write a ransom note or either criminal communication. Try the following activity to investigate one way to identify ink and the pen it came from.

Materials

- scissors
- coffee filters
- ruler
- water-soluble felt-tipped pens of different brands and different colors
- drinking glass
- tap water
- paper towel

Procedures

1. cut the coffee filters into several strips 1 inch (2.5 cm) wide.
2. Make a thick circle with one felt-tipped pen about 1 inch (2.5 cm) from the end of one strip.
3. Pour water into the drinking glass so that it fills ½ inch (1 cm) of the bottom of the glass.
4. Dip the end of the strip in the water so that the water covers about ½ inch (1 cm) of the end of the strip that you marked. The water should not touch the circle you drew.
5. Watch the water creep up the strip until it reaches the top of the strip.
6. Take the strip out of the water and place it on the paper towel. Above the filter, write the name of the color of the pen on the paper towel, using the same pen you used on the strip.
7. Repeat the experiment with the rest of the strips and pens.
8. Observe what happened to the circles made on the strips. What do you notice about the dyes in the pens?

More Fun Stuff to Do

Give a helper several different felt-tipped pens of the same color. Leave the room while your helper writes a short note, such as “Give me the money, or else!” on a coffee filter strip. Using the procedure you learned in the activity, can you tell which pen was used to write the note?

Explanation

Ink is complex chemical made up of several chemicals. Through a process called chromatography, complex chemicals like ink are separated into the chemicals of which they are made.

In this activity you performed an ink chromatography test. The colors of the inks separated in the different patterns because the ink colors are carried by the water at different speeds.

A forensic scientist can compare the chromatography pattern of the ink used to write a note with the chromatography patterns of several different known pens. This allows him or her to identify which pen was used to write the note.

Blood Identification

2008-05-12T00:34:00.000-07:00

A few drops of a red substance are found at the house of a missing person. Are the drops red paint, ketchup from a hot dog, or possibly blood? The identification of the substance is important and will help a detective know which way to direct an investigation. Try the following activity to see one way that investigators determine the identity of a red substance.

Materials
- eyedropper
- red watercolor paint
- ketchup
- blood (from the bottom tray of a meat container)
- plate
- tap water
- Hemastix (available from many drugstores)

Caution: Be sure to wash your hands thoroughly after handling raw meat.

Procedure
1. Use the eyedropper to place 1 drop of red watercolor paint, 1 drop of ketchup, and 1 drop of blood on the plate.
2. Add a drop of water to ech red drop to make sure that they do not dry out.
3. Put a Hemastix strip in each solution. What happens? What color does the Hemastix strip turn in each solution? What color indicates blood?

Explanation

The Hemastix change color in blood. A Hemastix strip contains chemicals that will react with the chemicals normally found in blood. This simple test is often done at the scene of a crime as a quick way to determine whether a substance is blood. Later, Samples are tested in the laboratory to confirm the field test. Other tests, such as bloodtyping or DNA profiling, give more detailed information about the blood and the individual it came from

Mystery Substances

2008-05-07T23:56:00.000-07:00

Any unknown substance found at a crime scene may be important evidence. The liquid left in a drinking glass might be a poison, or the residue found on a suspect’s hand may be gunpowder. As you know, forensic chemist perform many tests on unknown substances in order to identify them. Color, odor, and reaction to other substances are all clues to identify of an unknown substance. Try the following activity to perform another important tes.

Materials
- 1 ½ quarts (1.5 liters) tap water
- 2 quarts (2 liter) saucepan
- 2 red cabbage leaves
- timer
- colander
- plastic bowl
- marking pen
- masking tape
- 5 jar or glasses
- measuring cup
- 3 tablespoons (45 ml) concentrated lemon juice
- 3 tablespoons (45 ml) vinegar
- 3 tablespoons (45 ml) disitilled water
- 1 tablespoons (15 ml) baking soda
- 3 tablespoons (45 ml) ammonia
- pencil
- sheet of white paper
- adult helper

Proceduse
Note: This activity requires adults help.
1. Put the water in the saucepan. Tear the red cabbage leaves into small pieces and place them in the water.
2. Have your adult helper heat the water to boiling and boil the leaves for 5 minutes. Allow the liquid to cool.
3. Hold the colander over the bowl and have your adult helper carefully strain the leaves through the colander. Throw the leaves away.
4. Use the marking pen and masking tape to label jars from 1 to 5.
5. Pour about ½ cup (125 ml) of the cabbage juice into each jar.
6. Add the lemon juice to jar 1, the vinegar to jar 2, the distilled water to jar 3, the baking soda to jar 4, and the ammonia to jar 5.
7. Observe the color that each substance turns the cabbage juice, and record the the color on the chart similar to the one shown.

Caution: Be careful not spill the ammonia on your hands.

Jar Chemical Acid/Basic Colour
1 lemon juice acid
2 vinegar slightly acid
3 distilled water neutral
4 baking soda slightly basic
5 ammonia basic

More Fun Stuff to Do
Use the remaining cabbage juice, ½ cup (125 ml) at a time, to test various household substances. Set up new jars of cabbage juice, add the substances to the juice, and observe the color the juice becomes. Based on the color, use the chart to determine whether the substance is acid, slightly acid, neutral, slightly basic, or basic.

Explanation
There are many tests that forensic scientists perform on unknown substances. A forensic scientist will be first observe the unknown substance, gathering information about its physical characteristics, such as color, texture, Odor, melting point, and boiling point.

Next, the forensic scientist will test the chemical characteristics of the unknown substance. Certain substances are chemicals called acids or bases. Cabbage juice is a chemical indicator that changes color in the presence of an acid or a basie. If the substance tested is acid, the cabbage juice turns red. If the substance is basic, the juice turns green. Listed bellow are the expected results for this activity.

Jar Chemical Acid/Basic Color
1 lemon juice acid red
2 vinegar slightly acid pink
3 distilled water neutral dark purple
4 baking soda slightly basic light green
5 ammonia basic green

Litmus paper is another chemical indicator that can be used to test whether a substance is an acid or a base. You may have used litmus paper in school. The pH scale describes the strength of acid s or bases. Sensitive pH paper or pH meters tell not only whether the unknown substance is acid or basic, but also how strong the acid or basic is.

Taking Fingerprints

2008-05-07T21:22:00.000-07:00

People have noticed the subtle differences in the fingerprint patterns for hundreds of years. Centuries ago, Chinese and Japanese emperors signed papers with thumbprints to make them authentic. But it wasn’t until the late 1800s that fingerprints were used as evidence to link a suspect to a crime. The first step in understanding fingerprints-and fingerprinting-is to examine your own.

Materials
- magnifying lens
- ink pad
- several sheets of white paper
- marking pen
- pencil
- transparent tape
- helper

Procedure
1. Look at your fingerptips through the magnifying lens and examine the patterns on your skin. These are your fingerprints. Can you describe them in words?
2. Make a set of your fingerprints. There are two easy ways to do this.

Method I
a. Press one finger at a time into the ink pad, being careful not to get your fingers too wet.
b. Have your helper make your fingerprints by holding your hand steady and pressing and rolling your fingers one at a time onto a clean sheet of white paper. Be careful not to smudge the prints.
c. Use the marking pen to label each print with the name of the finger from which it camel thumb, index finger, middle finger, ring finger, pinkie.

Methode II
a. Rub the pencil point back and forth many times on a clean sheet of white paper to make a small dark area of pencil-lead dust.
b. Press one finger at a time into the dust. You may need to rub the pencil point again to get more dust for each fingerprint.
c. Have your helper place the sticky side of a piece of transparent tape on each dusted finger.
d. Tape the prints to another clean sheet of white paper.
e. Use the marking pen to label each print with the name of the finger from which it came.

3. Examine both types of fingerprints with a magnifying lens.

More Fun Stuff to Do
Using either methode. Create a complete set of fingerprints for each of several helpers. Use one sheet of paper for each set, and label the prints so that you know which fingers and which person they came from. Next, have each helper make a fingerprint on separate sheet paper. Do not label these prints. Choose one of the sheets of paper at random. Using your labeled sets of fingerprints, try to figure out whose fingerprint it is. What can you do to make the task easier?

Ask an adult arrange a trip to your local police station to observe how the police take fingerprints. How do their methode compare to the two methods you learned?

Explanation

The skin on the palms of our hands (and the soles of our feet) is covered with tiny raised lines, called friction ridges. These ridges allow people to pick up and handle objects easily. Each person, even an identical twin, has a totally unique pattern of ridges on his or her hands and feet. And for each person, the pattern on each finger or toe is unique and different from the pattern on every other finger or toe.

A fingerprint is an impression of these ridge patterns transferred to a surface. Fingerprints occur because glands in our hands and feet secrete liquids, mainly sweat and oils. These liquids leave the patterned mark of our fingerprints on almost everything we touch.

There are three ways that fingerprints are valuable as evidence. First, fingerprints can confirm the identity of a person. When a criminal is taken into custody, it is a fairly simple task to take his or her fingerprints and cross-check them against other prints. This will prove who the criminal is and determine whether he or she has a criminal record or whether he or she is wanted by the police.

Second. Fingerprints can be used to compare a suspect in custody with fingerprints left at the scene of a crime.
Third, forensic scientist can compare fingerprints left at the scene of a crime with those of a known criminal whose fingerprints are on record.

Lip Prints

2008-05-07T20:45:00.000-07:00

Women who wear lipstick often leave lip prints on drinking glasses. At a scene, this kind of print would be collected as evidence during an investigation. Try the following activity to learn how lip prints can be used to solve crimes.

Materials
- Lipstick (dark colors work best)
- White paper
- Pen or pencil

Procedure
1. Put lipstick on both of your lips. Rub your lips together to spread the lipstick evenly.
2. Fold the white paper in half.
3. Place the folded piece of paper between your lips and firmly press your lips against it. Be careful not to slide your lips on the paper or else the lip print will smudge.
4. Remove the paper and unfold it. Write your name on the paper to identify the lip print as yours.
5. Examine your lip print. What do you notice about it? Are there any unique qualities that would let you identify it as yours?

More Fun Stuff to Do
Collect lip prints from several helpers. Make sure that you write each person’s name next to his or her print. Then leave the room and have one of your helpers make a lip print on a drinking glass. Can you identify who made the print?

Explanation
There are many ways to identify a person. One of them is cheiloscopy, or the study of lip prints. (The term cheiloscopy comes from Greek word cheilos, meaning “lip”.) Lip prints are unique and do not change during a person’s life. Although they are less commonly encountered than fingerprints at the scene of crime, lip prints found on drinking glasses, cups, and even letters can be valuable evidence. One problem with lip prints is that their credibility has not yet been established in courts of law.

Mystery Powders

2008-05-07T17:53:00.000-07:00

White powder found at a crime scene or in a suspect's pocket may be an illegal substance or merely sugar. A detective will have a crime lab identify the substance to determine whether a crime has been committed. Try the following activity to learn how forensic chemists use chemistry to identify unknown substances.

Materials
- Pencil
- Sheet of white paper
- measuring spoon set
- baking soda
- sugar
- salt
- cornstarch
- 4 sheets of black construction paper
- white chalk
- magnifying lens
- eyedropper
- water
- 4 small jars
- iodine solution (available at most drugstores)
- dish towel
- vinegar

Procedure
1. Use the pencil and white paper to create a chart similar to the one shown bellow.
2. Put 1/4 teaspoon (1 ml) of each white powder (baking soda, sugar, salt, and cornstarch) on a separate sheet of black construction paper. Use the chalk to label each powder.
3. Examine each powder with the magnifying lens. What does each powder look like? What its shape? Are its grains large or small? Record your observations in the appearance column of the chart.
4. Rub each powder between your fingers. How does it feel? Record your comments in the Texture column.
5. Do any of the powders have a smell? If so, record that information in the Smell column.
6. Use the eyedropper to place a drop af water on each powder. What happens? Do any of the powders dissolve or react in any other way? Record the results in the Reaction to Water column.
7. Put ½ teaspoon (2 ml) of each powder in a separate jar. Use the eye dropper to add 2 drops of iodine solution to each jar. Observer what happens and record your observations in the Reaction to Iodine column.
8. Rinse and dry the jars.
9. Put ½ teaspoon (2 ml) of each powder in a separate jar. Use the eye dropper to add 2 drops of vinegar solution to each jar. Observer what happens and record your observations in the Reaction to Vinegar column.

Appearance:Texture:Smell:Reaction to Water:Reaction to Iodine:Reaction to Vinegar
Baking Soda:
Sugar:
Salt:
Cornstarch:

More Fun Stuff to Do
Can you identify a mystery powder? Have a helper give you a small amount of one of the white powders without telling you which one it is. Repeat the chemical tests on the mystery powder and compare your results to those on the chart to identify the powder. Check with your helper to see whether you were correct.

Explanation
The results of your tests in this activity should be similar to those listed in the chart bellow.
If you did the More Fun Stuff to Do Activity, you should have been able to identify the unknown substance by repeating the tests and comparing your results to the results listed in your chart.
Just as you did in this activity, forensic scientists use a variety of tests to identify an unknown substance. Some tests examine the physical characteristics of a substance, such as its color, shape, and so forth. Other tests explore how it reacts to an acid, and so on. Forensic scientists compare the results of tests done on unknown substances to the results of tests done on known substances to identify the unknown substances.