If you’ve ever looked closely at your own fingertips, you’ve probably noticed that the skin is grooved with very, very thin lines in a spirally pattern. That’s your fingerprint, and it is your very own: every single person has his or her own special pattern. There are six basic styles of fingerprints, though: loop from right, loop from left, arch, whorl, double loop, and “eclectic,” which basically covers all the weird remaining ones that don’t have a name. These grooves in our fingers help us grip objects — but as a special bonus, fingerprints also leave tracks showing exactly whose fingers they are. You can use your fingerprints on scanners to get permission to open doors, but your fingerprints can also show that you were the thief who opened the cookie jar. Just one more good reason to wash your hands.
Wee ones: There are 6 types of fingerprints, but half of those involve “loops.” How many loopy fingerprint types are there?
Little kids: If you have messy chocolate all over one hand, and you fully touch the table with that hand 3 times, how many total fingerprint marks do you leave on the table? Bonus: If 2 friends each have both hands covered with chocolate and they each rest all 10 fingers on the table, now how many total fingerprints are there?
Big kids: One way to see your fingerprint is to press your finger on an ink pad, then on a fresh empty balloon, and then blow up the balloon to watch the design stretch out. If your fingerprint covers a space that gets 5 times as tall and 5 times as wide when you inflate the balloon, how many of your original fingerprint could fit in that new space? Bonus: If that area now doubles in each direction, now how many times as big is it relative to your original fingerprint?
The sky’s the limit: Suppose your class at school has 12 boys and 12 girls, all with loop, arch or whorl fingerprints. If half the boys and 2/3 of the girls have loopy fingerprints, and half the remaining kids have arch fingerprints but that includes 3 more boys than girls, how many girls have whorls?
Wee ones: 3 loopy types.
Little kids: 15 fingerprints. Bonus: 35 fingerprints, since the friends added 20.
Big kids: 25 fingerprints. Bonus: 100 times as big.
The sky’s the limit: 6 boys and 8 girls have loops, leaving 6 boys and 4 girls with other types. Half, or 5 in total, have arches, but if that includes 3 more boys than girls, then only 1 girl has arches (along with 4 boys). That leaves 3 girls with whorls.