Look, Mom, I'm a Detective!
Teach kids that everything they touch, even with dry hands, leaves a bit of oil from their skin behind — just enough to gather a print. Using cocoa powder or ground-up pencil graphite, have them sprinkle the powder onto the area where the fingerprint was left. Using a small soft brush, they should gently remove the powder to reveal the print. Then, use a piece of clear tape and gently lift the print.