Animals don’t want other animals to eat them. So they find clever ways to hide. Some bugs and birds are the same color as the leaves or dirt around them, meaning they’re “camouflaged” and are hard to see. Chameleons can turn the same color as the colors around them in just minutes. But the mutable rainfrog from Ecuador might be the winner: it can change the shape of its skin, turning from smooth to spiky in just 3 minutes. This helps it blend in with tree bark and other scratchy stuff. Scientists studying it were at first really confused: they had scooped up the spiky frog in a cup, then an hour later it looked totally different! They wondered if the frog had swapped places with a friend. But no, he had just changed his skin — and had become a nicer, less prickly pet.
Wee ones: If the frog is spiky, then smooth, then spiky, then smooth…what shape does it take next?
Little kids: If you have 6 of these funny frogs in spiky mode and 1 more who’s smooth, how many rainfrogs do you have? Bonus: If the frog can switch from spiky to smooth in 3 minutes, then changes right back in the next 3 minutes, how many minutes did it spend changing its shape?
Big kids: If you make your hair go from flat to spiky, and it takes 7 times as long as the 3-minute rainfrog, how long does your hair change take? Bonus: If you start spiking your hair at 3:50 pm, when is it finally fully spiky?
Wee ones: Spiky.
Little kids: 7 frogs. Bonus: 6 minutes.
Big kids: 21 minutes. Bonus: At 4:11 pm.
Laura Bilodeau Overdeck is founder and president of Bedtime Math Foundation. Her goal is to make math as playful for kids as it was for her when she was a child. Her mom had Laura baking before she could walk, and her dad had her using power tools at a very unsafe age, measuring lengths, widths and angles in the process. Armed with this early love of numbers, Laura went on to get a BA in astrophysics from Princeton University, and an MBA from the Wharton School of Business; she continues to star-gaze today. Laura’s other interests include her three lively children, chocolate, extreme vehicles, and Lego Mindstorms.