FINGERPRINT CLUES
Fingerprints are formed by very fine ridges in the skin of the tops sections of your fingers. You can see them if you look carefully. The ridges are sensitive to touch and are there to help you grasp things. But what’s really cool is that no two fingerprints are alike! You’ve heard that every snowflake is different? Same with fingerprints.
There are recognizable patterns in fingerprints that detectives use for identification purposes. For example, if a detective has a record of what your fingerprints look like, and then finds the same fingerprints on the side of a drinking glass, the detective will know that you touched it – possibly a clue to who drank the juice in that glass!
Let’s give it a try with your own fingerprints.
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Click on the image below for a printable PDF of this “Fingerprint Patterns” chart to use with this doable.
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First of all, you will want to make a record of your fingerprints for comparison purposes.
You will need:
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Pieces of white paper
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Clear cellophane tape
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Graphite pencil
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Magnifying glass (homemade, toy, or real, although the better the magnifying glass, the easier it will be to examine the prints)
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Optional: cocoa powder
Steps:
1. Make a “stamp pad”: On a piece of paper, scribble a patch using the side of the pencil tip, creating a fine layer of graphite shavings. Alternatively, tip a very small amount of cocoa powder on to the paper, and spread it out so that it is barely visible.
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2. Prepare for the record on another piece of paper: Have a pencil ready to label the prints as they are made, or draw an outline of a hand to which the prints will be adhered.
3. Collect the prints: One at a time, roll the flat tip of a finger in the graphite shavings or the cocoa powder, leaving a barely visible, even coating on the finger.
Take a 2” piece of clear tape, and press the coated fingertip on to the sticky side. When the tape is pulled off, a fingerprint should be visible on it.
Attach the piece of tape to the record, either at the labeled location or on the drawn finger corresponding to the print just taken.
Move on to the next finger, until you have collected all ten on your record.
Note, powdered sugar or flour can be substituted for the cocoa powder, but then you will need to adhere them to dark colored paper.
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Using a magnifying glass, look carefully at each print. Can you find whorls, loops, or arches?
Now, let’s play detective and check out the fingerprints on a glass.
You will need:
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Cocoa powder OR powdered sugar OR flour
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White paper (if using the cocoa powder) or dark paper if using the powdered sugar or flour
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Fine, soft paint brush or makeup brush
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Cellophane tape
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A clear drinking glass, polished so it has no prints on it already
Steps:
1. Rub your hand on your cheek, nose, or forehead to pick up a little oil from your skin. Then wrap your hand and fingers around the drinking glass to leave fingerprints on it.
2. Brush a light coating of the cocoa powder over one of the prints on the glass, and gently blow away the excess.
3. Press a piece of the clear tape over the cocoa powder print, and lift it off. Then tape it to the paper so you can look at it.
4. Compare the lifted print to the record of your fingerprints. Can you find a match? Aha! You are the one who held the glass. Great detective work!
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This doable can be expanded with family and friends, collecting multiple records and then comparing them with fingerprints lifted from refrigerator handles, cabinet doors, toys. Where a lot of fingerprints show up, you can use clear packaging tape to collect more than one print at a time.
Bonus fun:
Check out Ed Emberley’s Great Thumbprint Drawing Book. It provides step-by-step sketches for transforming thumbprints into characters, flowers, even trains. At the end it gives suggestions for alternatives to the usual stamp pad.
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Maybe there should be a prize (an extra thumbprint cupcake perhaps?) for the funniest thumbprint drawing in your house!
