You have the ability to pick up small objects because you have a very special thumb. It can move in many directions. We call this type of thumb an oposable thumb. To aide in helping you pick things up, nature has put small grippers in your fingers. The grippers have high and low points on them. The grippers form patterns and designs. We call these designs fingerprints.

Close up of a finger tip showing
the high and low points

The HIGH points are called
hills, while the LOW points
are called valleys

The edges of the penny are higher
than most of the features. When
pressed onto an ink pad, only the
high items touch the surface of
the ink pad. Only the high items
get ink on them. The lower
features, such as the area around
Lincoln's head, never touched the
surface of the ink pad. When
pressed onto paper, only the outer
egde and part of Lincoln's beard
make a mark on the paper.

Your fingerprint is like this too.
The hills or ridges stick up and get
ink on them. The hills and ridges
leave a mark on paper as does the
outer edge of a penny. The white
lines on a fingerprint are the
valleys or spaces between the
hills. These areas never got ink on
them because they were lower
and never reached the ink pad.
1)  Define these terms (Look in a dictionary)
  1. Depression
  2. Cross Section
  3. Pore
  4. Ridges
2)  Why does ink not get into the valleys on your finger?

3)  How do the prints on your fingers help you?