Mouse + Kangaroo = ?…

Here's your nightly math! Just 5 quick minutes of number fun for kids and parents at home. Read a cool fun fact, followed by math riddles at different levels so everyone can jump in. Your kids will love you for it.

Mouse + Kangaroo = ?…

September 28, 2018

Wouldn’t you love to have this animal as a pet? And what kind of animal is it, anyway? It’s a jerboa, a tiny hopping mouse that lives in the desert. It really can hop like a kangaroo: even though it’s only 3 inches long, it can hop at 15 miles an hour! That’s 5 times as fast as we giant humans walk. Its ears are longer than its whole head, and its tail can be longer than its whole body. The math gets even crazier when it comes to housing: the jerboa lives in 4 different burrows. It has 1 burrow for hiding during the day while out hunting; 1 for hiding at night while hunting; 1 “full-time” burrow for summer; and finally 1 full-time winter home. We hope the jerboa can remember directions as well as it can hop.

Wee ones: If you had 1 little house for the spring, 1 house for summer, 1 house for fall and 1 more for winter, how many houses would you have in total?

Little kids: How many ears do you and that jerboa have together?  Bonus: The jerboa has 4 legs, including 2 tiny front ones. If there are 10 legs in the room, how many jerboas could there be, and how many people if there’s at least 1 of each?

Big kids: How many times as tall as a 3-inch jerboa is a 60-inch-tall human?  Bonus: If a 3-inch jerboa can hop 15 miles an hour, how fast could that 60-inch human hop if people were just as fast compared to their height?










Wee ones: 4 houses.

Little kids: 4 ears.  Bonus: There could be 1 jerboa and 3 people, or 2 jerboas and just 1 person.

Big kids: 20 times as tall.  Bonus: 300 miles an hour!

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About the Author

Laura Overdeck

Laura Overdeck

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.

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