Science Projects Index
Comparing Finger Prints
Children, you know what the finger prints are. The fingerprints of no two people are alike. Different persons have different fingerprints. Criminals are often identified from their fingerprints.
To see the differences in the fingerprints, let's carry on a simple activity.
Take three sheets of paper and draw five squares on each sheet. Each square should be of two inches. Call two of your friends to help you. Write the names of your friends on the back of two sheets. On the third sheet, write your own name. Now take a stamp pad and sprinkle a little ink on it. Roll your thumb on it and put an impression of your thumb in the first square of your sheet. Next make impressions of each of your fingers in each square. Your friends should also make the impressions of their fingers in the squares on their sheets of paper. Immediately wash your hands to remove the ink stains. Mix the sheets and put them aside.
Next take a glass and clean it with a piece of cloth. After 15 minutes, ask one of your friends to hold the glass. He should hold it with the same hand with which he has fingerprinted. Let him put it aside. Then you pick up the glass by putting your hand inside it. With a painting brush apply some talcum powder on the fingerprints on the glass. Then paste a clear cling film on the print. And lift it off the glass. This piece of film is then to be pasted on a black paper. The impression should be facing the paper. With a magnifying glass see the prints on the black paper and on the sheets of paper. Compare the two prints. You will find that your fingerprints on both the papers are same. Similarly, your friend's fingerprints are also same. This is because one set of fingerprint can belong only to one person. The criminals try to remove their fingerprints from the site of crime so as to escape. If they leave their fingerprints behind, they are sure to be caught.