Dogs love to run with us, and usually the dog is faster. But it’s hard for dogs to keep up when we ride our bikes, because bikes go too fast. Well, some clever person has solved the problem. The machine in this picture is a stationary bike with a treadmill for your dog! A stationary bike is just a bike that stands still: you sit and pedal to spin the wheel. A treadmill is a flat, wide, bouncy moving belt that slides backward. So as you run forward on it, you don’t go anywhere (you just have to run fast enough not to go backward and fall off). Here, the biker’s pedaling makes the treadmill belt move, set at the perfect speed for any size dog. Now we can all exercise together — and the dog won’t run off to chase squirrels.
Wee ones: Pretend you’re the dog, and run 8 steps in place! Don’t go anywhere!
Little kids: How many feet do the biker and the dog have together? Bonus: If the dog runs 10 steps at a time, then rests, how would you count up the first 70 steps by 10s?
Big kids: If the biker and dog run for 15 minutes outside, but then the dog chases squirrels for another 15 minutes, how long does the dog run? Bonus: If the dog says “woof!” after the 5th step, then the 10th, then the 16th, then the 23rd…after what step does the dog woof next?
The sky’s the limit: If for each dog step the biker has to step (pedal) 3 times, at what point has the biker taken 240 more steps than the dog?
Wee ones: Count as you run in place: 1, 2, 3, 4, 5, 6, 7, 8!
Little kids: 6 feet. Bonus: 10, 20, 30, 40, 50, 60, 70.
Big kids: For 30 minutes. Bonus: After the 31st step. The dog waited another 5 steps to reach 10, then another 6 steps, then another 7…so the woof comes 8 steps after that.
The sky’s the limit: When the biker has taken 360 steps, and the dog has taken 120. If the biker always takes 3 times as many steps, that number is the number of dog steps, plus that dog-step number 2 more times. So the gap of 240 is 2 times the number of dog steps. (If you wanted to use algebra, where the dog’s steps are the mystery number d, you’d say h = 3d, so the different between them is 3d – d = 2d = 240.)
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.