Amusement parks have the biggest, fastest water slides rides you’ll ever ride — unless you build one the same size in your backyard! Grandpa Paul Betts saw an amusement park in England throwing out an old waterslide. He bought all the giant tube pieces from them for just 50 pounds (about $65 at the time of writing), then brought them to his grandkids’ house. With 18 sections each almost 10 feet long, the slide stretches 130 feet across the land, even with all the twists and turns. That’s the length of several houses! They can slide on it dry, but in the summer they run water through it and put a splashy pool at the bottom for the landing — because by the end they’re sliding pretty fast.
Wee ones: What shape is the opening of the waterslide tube?
Little kids: If the grandpa, the mom, the dad, and the 2 kids all ride the waterslide, how many people get to ride it? Bonus: If they start off connecting just 3 10-foot pieces, how long a slide do they make? Count up by 10s!
Big kids: If the grandpa, mom, and her son Oscar line up to take turns, how many different ways can they line up? Bonus: If a normal slide is 6 feet long, and this one has 18 10-foot sections, how many times as long as a normal slide is this crazy slide?
Answers:
Wee ones: An oval, or it might be a perfect circle when not squished.
Little kids: 5 people. Bonus: 30 feet: 10, 20, 30.
Big kids: 6 ways: GMO, GOM, MGO, MOG, OGM, OMG! (There are 3 choices for the 1st rider, then for each of those there are 2 choices for the 2nd, and the 3rd is set, giving us 3x2x1). Bonus: 30 times as long! 18 1-foot sections would be 3 times as long in total, so making them 10 feet multiplies that by 10.
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.