Image of a fingerprint on the side of a balloon.

The patterns on your fingerprint stay mostly the same throughout your life.

Have you ever wanted to know how experts identify fingerprints? This quick activity will make your fingerprints giant, to make clues easy to spot!

You will need

  • Stamp pad
  • White balloon


What to do

  1. finger pressing onto a stamp pad.Put your finger on the stamp pad.
  2. Pressing an inky finger onto a deflated balloon.Put a fingerprint onto the balloon.
  3. washing hands under a running tap.Go and wash your hands while you wait for the print to dry.
  4. Blowing up the balloon.Blow up the balloon and tie it off.
  5. Enlarged fingerprint on the balloon.Marvel at your fingerprint!


What’s happening?

Almost everyone has fingerprints. These wonderful patterns of ridges and gaps are super useful.

You might think that your fingerprints are there to improve your grip. However, experiments don’t seem to agree with that idea. Instead, it looks like they help improve your sense of touch, amplifying the vibrations caused when you brush against a surface. Forensic fingerprint experts, including some police, also use fingerprints for a different reason – identification!
The patterns on your fingerprint stay mostly the same throughout your life. And they have all kinds of little details that make them unique. It can be hard to see these details by just looking at your fingertips, but they should be much easier to spot when they’re blown up big on your balloon.

Fingerprints come in many basic patterns. Most are simple loops which start on one side, go around the middle and back to the same side. Whorls have circular lines around the middle, and arches start on one side, go up and over the middle and out the other side. There are also fingerprints that don’t fit into these patterns.

The real power of fingerprinting comes from the details. If you look closely, you’ll spot all kinds of details in your fingerprints. There are places where a line ends or begins, or places where they split or join up. You might have a very short line, or a spot where a line splits into 2 and then joins up again.

It takes more than one detail to identify a fingerprint. But if 2 fingerprints share a lot of details, in exactly the same places, you can be pretty sure they came from the same finger!

If you’re after more science activities for kids, subscribe to Double Helix magazine!

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