Have you ever stayed in the bathtub or pool so long that your fingers turned wrinkly? Why does this weird thing happen? Scientists figured out that the wrinkles help us pick up things underwater. Scientists asked people with dry fingers and people with wet, wrinkly fingers to pick up and move wet and dry marbles. The wrinkly-fingered folks got a much better grip on them. They didn’t drop them as easily, and could move them 1/8 faster: for every 8 marbles the dry fingers moved, wet fingers could move 9 in that same time. Long ago, these puckered fingers may have helped cavemen catch fish more easily in rivers and streams. As for you, it’ll help you pick up that rubber ducky.
Wee ones:If you pick up the 1st rubber ducky, then the 2nd ducky, then the 4th ducky, what number ducky did you skip in between?
Little kids: If you have 2 rubber duckies, 3 toy boats and a beach ball in the tub with you, how many toys do you have? Bonus: If a dry-fingered person picks up all the toys but then drops half of them, how many bath toys are dropped?
Big kids: If you can dive to the bottom of the pool and stay there 9 seconds, and you pick up 3 pennies off the pool floor every second, can you pick up 25 cents in time? Bonus: If instead there are 2 rubber duckies, 3 toy boats and a penny stuck on the floor of the pool, how many different pairs of things can you pick up? (Assume the 2 duckies are identical, and so are the 3 boats – but the order you pick up doesn’t matter.)
Wee ones: The 3rd rubber ducky.
Little kids: 6 toys. Bonus: 3 toys.
Big kids: Yes! You can pick up as many as 27 pennies. Bonus: 5 possible pairs: 2 ducks, duck + boat, duck + penny, 2 boats, and boat + penny.
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.