Discuss that fingerprints make each person unique from one another. The patterns formed on the fingertips are developed before we are born. These ridges provide extra grip without changing the sensitivity of the fingertip.
Demonstrate that fingerprints are left everywhere we go by showing the child a fingerprint you left earlier on something such as a glass of water. The print comes from the accumulation of oil and dirt our fingers produce and encounter.
Create fingerprint rubbings for children to see their own fingerprints using a pencil and paper. Rub the pencil on a piece of paper and have the child push her finger into the graphite. The child then presses her finger onto a piece of paper, leaving a print. Have the child print each finger to see the differences between the patterns on each finger and each hand.
Transfer the print to another piece of paper using tape. Press clear tape over a print and rub your finger over the top of the print. Carefully remove the tape and place it onto another piece of paper.
Discuss with the child that fingerprints are used to identify people. Criminal investigators use fingerprints to identify criminals who leave their fingerprints at crime scenes.
Compare fingerprints to one another. Fingerprints usually come in three distinct pattern formations: whorl, which is a spiral-type shape; loop, a long pattern that circles back on itself without touch, and arch, which is a hump pattern. Have the child identify these patterns in the fingerprints.