When it comes to naming things, sometimes we get lazy. A shoe for horses — a horseshoe. A house up in a tree — a treehouse. And the ride that goes round and round and makes us merry — a merry-go-round. But that really is the perfect name for it. Merry-go-rounds, also called carousels, are all silly, and all different. They have different numbers of animals; some have 2 levels instead of 1; and they turn at different speeds. Sometimes the animals stand 3 side by side, so there’s an inner ring, a middle ring and an outside ring. Usually when they do this, the smaller kinds of animals (like rabbits and foxes) go in the innermost ring, with the biggest animals on the outside. Today is National Merry-Go-Round Day, so let’s try doing the math about it!
Wee ones: If a merry-go-round has horses, giraffes, zebras, lions, cows, and tigers, how many kinds of animals does it have?
Little kids: If you ride the horse, then the zebra, then the lion, then the horse again to repeat, what do you ride next? Bonus: If on 1 spin of the merry-go-round you go up 6 times and down 6 times, how many movements do you make?
Big kids: If your horse goes up and down 6 times as you go around once, how many times do you go up and down on 4 spins? Bonus: If the animals are in rows of 3, how many rows do you need if you want to give seats to at least 50 people?
Wee ones: 6 kinds of animals.
Little kids: The zebra. Bonus: 12 movements.
Big kids: 24 times. Bonus: You need at least 17 rows, because 16 rows will give you only 48 seats.
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.