Investigating fi ngerprints

1) Observation

First, you might want to start out by simply looking at your fi ngertips. This sounds simple and obvi- ous, but most people go through their entire lives without seeing their skin close up. You will need magnifi with at least 10x, and higher is better. Amazon carriers a few magnifi ers that are advertised as 40x, which is plenty of magnifi cation. You will likely see tiny pieces of dirt embedded here and there, which you really can’t see with just your eyes. (While you are at it, take a look at what is under nails. Pull the skin down a bit to get a bet- ter view.)

2) Make a set of fi ngerprints

Use a stamp pad (black ink is best) and a copy of the chart on the next page, to make a set of your fi ngerprints. Fingerprints are being used more than ever to establish identity. You probably know someone who had to get fi ngerprinted as part of a “background check” for a job or a volunteer position. Use the fi ngerprint classifi cation chart to try to classify each of your fi ngerprints. There is an additional page that lets you learn a little more about what fi ngerprint experts look for when the classify prints. They look for places that the ridges intersect or form particular patterns.

3) Optional edible craft demonstrating the anatomy of a fi ngerprint

You will need: a graham cracker (or other large, fl at, stiff edible biscuit), some chocolate chips, a little bit of icing (to use as edible glue) and a piece of fruit leather (a wide piece, not a strip) The graham cracker will represent the dermis. The chocolate chips will represent the dermal papil- lae. The fruit leather will the epidermis. The icing doesn’t represent anything, you just need it to stick the papillae on the dermis. Use the icing to stick the chocolate chips to the graham cracker. Make them form lines, the way real papillae do in the fi ngertips (as in picture). Then place the fruit leather (gently) on top of the whole thing, and very carefully press it down, pushing it into the spaces between the lines of chips. You now have an edible model of showing how the dermal papillae cause the ridg- in the epidermis. Can you classify each of your fingerprints? Look for these “minutiae” (min-ue-shah) patterns in the above fingerprints. (You might want to use a highlighter or colored pencil to circle or mark them.)