To do this experiment, have the child firmly place her index finger on the side of the glass. If her finger is a little bit sticky or oily, the fingerprint will show up more clearly. Lightly coat the fingerprint with the cocoa powder. Dust away the excess cocoa powder gently to reveal the fingerprint. Put a piece of tape over the fingerprint to lift it off of the glass, then put the tape on a piece of light-colored paper to save it. Notice if the fingerprint is an arch, loop or whorl pattern, and label it as such. Have the child collect other fingerprints from classmates, friends or family, and determine which is the most common fingerprint pattern and what is the least common pattern.
For this experiment, you'll need a group of between three and eight people. Collect the fingerprints from all participants using the method in the previous experiment. Make sure to use the same colored paper for every person. Have each person write his name on the back of the paper, and study his fingerprint pattern until he thinks he has it memorized. Take all of the papers with the fingerprints and shuffle them around. Next, lay them out on a flat surface like a table or floor, and have everyone try and pick out his own fingerprint. See who can recognize his fingerprint pattern in the first try.
Have the child collect his fingerprint, and write his name on the paper. Have him label it as a whorl, arch or loop pattern. Next, tell the child to collect the fingerprints from his family, including extended family, if possible. Each fingerprint should be labeled with the person's name, her relation to the child and as an arch, whorl or loop pattern. See if the child can notice any correlation between heredity or relation and fingerprint pattern.
Try using different kinds of drinking glasses to see what the fingerprints look like on each of them. You could use a frosted glass, for example, or a glass with beveled designs. Place a fingerprint on each glass and collect it with the tape. After you collect the fingerprints from these glasses, compare what the fingerprints look like to a fingerprint taken from a smooth drinking glass. Are they more difficult to see? Do they look smeared or distorted in some places?