Kids love playing detective in this experiment. And investigating the science of fingerprints only requires a magnifying glass, a pencil, and some tape! Throw in some cocoa powder and a brush to let your kids try their hand at print lifting and identification for some additional fun learning.
To study fingerprints, you’ll need:
- white paper
- clear tape
- a pencil
- a magnifying glass
To lift prints from a glass you’ll also need:
- a clear glass or jar
- cocoa powder
- a paintbrush or makeup brush
How to Study Fingerprints
Step 1: Have your kids trace their hands on white paper, using a pencil. (For smaller children, you can help them do this step.)
Step 2: On a different piece of paper, scribble hard with pencil until a small area is covered with graphite. Ask your kids to rub their left pinkie around in the graphite until it is covered with gray.
Step 3: Carefully, help your kids place their left pinky finger on the sticky side of a piece of clear tape, then gently lift their finger off of the tape. A clear fingerprint should be visible.
Step 4: Have them place the tape face-down on the left pinky finger of each of their traced hand.
Step 5: Have your kids repeat this with each finger of their left hand until they have fingerprints on each of the five fingers traced. Now do it with their right hands. Most older kids will get the hang of it quickly and be able to do it themselves.
Step 6: Let your kids inspect their fingerprints under a magnifying glass, if you have one. (Even if you don’t, they’ll be able to see patterns.) Ask them whether the prints are the same on each hand and whether they see any patterns like loops or arches.
To Lift Prints
Step 1: Ask your kids to rub their hands together and to make several clear fingerprints on a tranparent glass.
Step 2: Using a brush, have your kids very gently dust some cocoa powder onto one of the fingerprints on the glass.
Step 3: Ask them to blow the excess cocoa powder away and let them lift the fingerprint with a piece of tape. It may take some practice.
Step 4: Tape the fingerprint onto a piece of white paper and ask them to try to match it to one of the fingerprints from the first part of the experiment. Can they figure out which finger it came from?
Bonus exercise: For kids who want even more detective work, have them make fingerprint profiles for each of your family members by dusting the water glasses from the table after dinner to identify who used each glass.
The Science Behind the Fun
Fingerprints are the impressions left by skin ridges on human fingers. These ridges help us feel things and grip objects. The scientific study of fingerprints is called dermatoglyphics. (Derma means skin and glyphics means carving.)
No two people have identical fingerprints, but fingerprint patterns tend to run in families. These patterns often look like whorls, loops, or arches, and fingers often leave imprints of sweat and oil behind. These unique prints are essential to many crime scene investigations.
You can find more experiments like this one at kitchenpantryscientist.com, and in my books Kitchen Science Lab for Kids (Quarry Books) and Outdoor Science Lab for Kids (Quarry Books).
© Quarry Books, 2016/Kitchen Science Lab for Kids
Featured Photos Credit: © Quarry Books
