Earth is a huge ball in space. All our houses, roads, trees and lakes are just tiny dots compared to Earth. So our fan Brayden B. asked a great question: How many buildings placed end to end would it take to stretch all the way around the world? (And drew this neat picture to go along with the question!) Well, it depends how big a building! A building that’s twice as long as another will need only half as many to stretch those 25,000 miles. The average house is about 120 feet long, so we’d need 44 of them just to span 1 mile, or over 1 million houses to go around Earth! But a treehouse is much smaller, while Michelin Tire’s building in South Carolina is a whopping 3,600 feet long — we won’t need as many of those! Check out the math to see what happens.
Wee ones: The Earth we stand on is a giant ball in space. Can you find 2 ball shapes in your room? If you can, which one is bigger?
Little kids: Some buildings are taller than they are wide, while others are wider than they are tall. Which kind of building is your home? Look at a picture, or step outside to look at it! Bonus: If you line up 7 10-foot-wide treehouses in a row, how far do they stretch? Count up by 10s!
Big kids: If your new treehouse is 50 feet long, how many of those houses do you need to stretch 1 mile? (You can round off to 5,000 feet in a mile if you want to estimate!) Bonus: And then how many of those treehouses would it take to stretch the 25,000 miles around Earth? (Hint if needed: First see how many if there were just 10 treehouses per mile…)
Wee ones: Items might include anything from a marble to a soccer ball or beach ball.
Little kids: Different for everyone…apartment buildings are often taller than wide, but many single-family homes are wider than tall. Bonus: 70 feet: 10, 20, 30, 40, 50, 60, 70.
Big kids: About 100 treehouses. Bonus: 2,500,000 treehouses (2 million 500 thousand).
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.