Dermatoglyphics (Forensic Fingerprints)

Materials

Pick Up Kit

• 2 Sheets of white paper
• Transparent tape (scotch tape)
• Magnifying glass
• Pencil
• Unsweetened cocoa powder
• Paintbrush

Home Materials

• Clear glass or jar

What to Do

1. On one sheet of paper, trace your hand with a pencil.
2. On the other piece of paper, scribble hard with the pencil until a small area is covered with the graphite from the pencil lead.
3. Rub your pinkie around in the graphite until it is covered with gray.
4. 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.
5. Place the tape facedown on the pinkie finger of the hand you traced.
6. Repeat steps 3-5 with each finger until you have finger prints on each of the fingers you traced.
7. Inspect the fingerprints under a magnifying glass.
8. Rub your hands together to spread the oil on your skin around, then make several fingerprints on the clear glass.
9. Using a brush, gently dust some cocoa powder onto one of those fingerprints on the glass.
10. Blow the excess cocoa powder away and lift the fingerprint with a piece of tape.
11. 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.