Dermatoglyphics (Forensic Fingerprints)
Pick Up Kit
- 2 Sheets of white paper
- Transparent tape (scotch tape)
- Magnifying glass
- Unsweetened cocoa powder
- Clear glass or jar
What to Do
- On one sheet of paper, trace your hand with a pencil.
- On the other piece of paper, scribble hard with the pencil until a small area is covered with the graphite from the pencil lead.
- Rub your pinkie around in the graphite until it is covered with gray.
- Carefully place your graphite-covered pinkie finger on the sticky side of a piece of transparent tape and gently lift your finger off the tape. A clear finger print should be visible.
- Place the tape facedown on the pinkie finger of the hand you traced.
- Repeat steps 3-5 with each finger until you have finger prints on each of the fingers you traced.
- Inspect the fingerprints under a magnifying glass.
- Rub your hands together to spread the oil on your skin around, then make several fingerprints on the clear glass.
- Using a brush, gently dust some cocoa powder onto one of those fingerprints on the glass.
- Blow the excess cocoa powder away and lift the fingerprint with a piece of tape.
- Tape the fingerprint onto a piece of white paper and try to match it to one from your hand. Can you figure out which finger it came from?
What to Talk About
- Skin’s outer layer is called the epidermis, and a fingerprint is the impression left by epidermal ridges on human fingers. These ridges help us feel things and grip things better.
- No two people have identical fingerprints, but patterns can run in families. Let’s wonder if the people in our families might have fingerprints that are similar to ours.
- These patterns tend to look like whorls, loops or arches, and fingers often leave imprints of sweat, oil, ink or other substances behind.
- Fingerprints are often essential tools in crime scene investigations.
- It might be neat to collect water glasses from the table after a meal. Do you think you might be able to identify who used each glass?
- I wonder if we could do this same activity using cornstarch and black paper and how it might compare to the graphite.