When you put cheese on a hamburger, you get a cheeseburger. When you combine a spoon with a fork, you get a spork. But what do you get when you put a zebra with a giraffe? You get something like the okapi, a strange animal from the middle of Africa. It has the stripes and short neck of a zebra, but is a closer cousin of the giraffe. Only its legs, tummy and butt have stripes, maybe so baby okapis can see and follow their mom through the tall grass. Like a giraffe, the okapi eats leaves from trees using its tongue, which is so long that an okapi can lick its own eyelids and ears to clean them! But unlike a giraffe, okapis stand only about 5 or 6 feet at the shoulder, while their giraffe cousins are about 3 times as tall. Maybe okapis feel like they fit in better with the zebras.
Wee ones: How many legs does an okapi have?
Little kids: If you pat a white stripe on the okapi, then a black stripe, then a white, then a black, what are the next 3 stripes you pat after that? Bonus: Baby giraffes start out tall. If a 6-foot okapi hangs out with his 11-foot baby giraffe cousin, how much taller is the giraffe?
Big kids: A giraffe’s tongue is about 20 inches long — almost 2 feet! If your tongue is 5 inches long (starting from the back of your head), how many of your tongue end to end would match a giraffe’s tongue? Bonus: We can’t tell you how tall our pet giraffe is, but if you take its height in feet, double it and add 5, you get 43. How tall is the giraffe?
The sky’s the limit: If giraffes, okapis and zebras are all hanging out together, and there are twice as many giraffes as okapis but twice as many striped animals as giraffes, and there are 12 more zebras than okapis, how many are there of each animal?
Wee ones: 4 legs.
Little kids: White, black, white. Bonus: 5 feet taller.
Big kids: 4 of your tongue. Bonus: 19 feet.
The sky’s the limit: 6 okapis, 12 giraffes, and 18 zebras. If there are twice as many okapis and zebras together as giraffes, and the okapis are half the giraffe number, then the okapis are just 1/4 of the “stripe” total. Zebras have to cover the other 3/4. So there are 3 times as many zebras as okapis. That gap of 12 is like two more of those sets of okapis. That gives us 6 okapis and 18 zebras. That means there are 24 striped animals in total; giraffes are half of that, giving us 12 giraffes. So we did end up with twice as many giraffes as okapis.
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.