Be a Junior Detective: Fingerprints and Footprints

Someone ate all the cookies from the kitchen jar! There is a trail of crumbs leading to the back door, a sticky chocolate fingerprint on the counter, and one small muddy footprint by the door mat. A real detective doesn't guess who did it — a real detective follows the clues. Today, you get to be that detective.

- What a clue is and how it helps solve a mystery - Why every person's fingerprint is different - How footprints show size and direction - How to use a magnifying glass like a real detective

A clue is a piece of evidence that helps you figure out what happened. The crumb trail from the cookie jar to the back door is a clue — it tells you which way the cookie-eater went. On their own, clues might seem small, but a detective puts many small clues together to solve the whole mystery.

Look closely at your fingertip and you will see tiny curvy lines called ridges. No two people in the world have the exact same pattern of ridges — not even identical twins! Real detectives call these patterns loops (lines that curve and come back), whorls (lines that spiral like a circle), and arches (lines that rise up like a little hill). When a detective finds a fingerprint at a scene, they can compare its loops, whorls, and arches to find out whose hand touched it.

A footprint can tell you a lot. Its size can hint at whether it belongs to a grown-up or a kid. The direction the toes point tells you which way that person was walking. And how deep or muddy the print is can even hint at whether they were walking slowly or running fast!

Let's put it together: the crumb trail points toward the back door, so that's the direction the cookie-eater went. The chocolate fingerprint has big loopy ridges. The muddy footprint is small, about the size of a kid's shoe. All three clues point to the same detective conclusion: a kid with chocolate on their hands went out the back door!