Just select one of the four modes to scan and point the camera at the child's hands. If they are dirty, select the mode with lots of germs. After your children done with washing, show them how clean their hands are with a zero germs mode. Use share button to send 'before' and 'after' photos to your relatives and friends. If kids remember ordinary microbes, use another set: we have developed both sweet and evil ones. It's great learning app. Just try it!