Hey, is that a real live monster-sized alligator? Luckily, no. It’s an alligator made of rice straw. Every year in Japan the rice harvest leaves straw that you can’t eat. So people bundle and braid the straw into GIANT animal sculptures. Judging from the bridge, this full-length alligator is probably over 10 feet tall and 30 feet long, about twice as long as a car! The artists also made a giant lion, gorilla, and other animals — check them out here! And how much straw do they use? What do they weigh? Let’s do the math to find out.
Wee ones: What shape do the alligator’s teeth look like?
Little kids: Are there more big teeth or small teeth in the alligator’s top jaw? Bonus: How many more big teeth than small teeth does the top jaw have?
Big kids: If there are 5 giant sculptures and each used 200 bales (box-shaped bundles) of straw, how many bales were used? Bonus: If a bale weighs 40 pounds, how much does a 200-bale animal weigh?
The sky’s the limit: A sculpture uses a “mystery number” of bales. We can’t tell you what it is, but if you take that number, add 10, then divide by 10, then square that number (multiply that number by itself), you get 361. What’s the mystery number?
Wee ones: A triangle (from the side view), or in 3D, a cone (rounded pointed shape).
Little kids: There are more big teeth. Bonus: 4 more teeth, since we see 8 big teeth and 4 smaller teeth.
Big kids: 1,000 bales. Bonus: 8,000 pounds!
The sky’s the limit: 180 bales. Working backwards, we need the square root of 361, meaning a number that multiplies by itself to get 361. Your clues are that it’s near 400, which is 20×20, and it ends in a 1…only numbers ending in 1 or 9 can multiply by themselves and still get a 1 at the end. That gives us 19. We divided by 10 to get there, which gave us 190; and we added 10 to get there, which gives us 180.
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.