What do dogs, tigers, skunks, and dolphins have in common? They all have tails. Most tails are round: if you looked at the tail head-on from the tip, you’d see a circle (its “cross-section”). But the seahorse’s tail is square. It’s actually a stack of 36 square plates, like the bumps in your spine; each square is made up of 4 L-shaped bones. Scientists were so curious about the square tail that they made a plastic model of it to study. They figured out that a square tail is actually stronger than a round one, making it better for grabbing onto sea grasses and other things. The squares also snap back into place faster, so it takes less energy to move the tail. Scientists think this could help them build stronger robots, in case those robots ever need to grab some seaweed for dinner.
Wee ones: How many sides does a square have?
Little kids: Seahorses swim really slowly, only about 5 feet per hour. Take 5 slow steps and count them starting with the number 4. What numbers do you say? Bonus: Seahorses can be as long as 14 inches. If your pet seahorse is just 1 inch shorter than that, how long is it? How does that compare to your hand?
Big kids: A mama seahorse can lay up to 1,500 eggs at a time. If she’s laid 1,100 so far, how many more could she lay? Bonus: If every 4th tail plate of the 36 (starting with the 4th) has a pink L in it, and every 6th plate starting with the 6th has a blue one, what’s the first plate that has both?
Answers:
Wee ones: 4 sides.
Little kids: 4, 5, 6, 7, 8. Bonus: 13 inches, which is a lot longer than your hand!
Big kids: 400 more eggs. Bonus: The 12th plate, since it’s divisible by both 4 and 6.
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.