Jump rope is fun, but it’s tricky. Every time the rope whizzes at your feet, you have to hop over. Well, a group of girls from Ohio called the Firecrackers has jacked up jumprope to a whole new level. As you can see in this video, the girls crisscross their ropes, jump through each other’s ropes while galloping sideways, and even “jump” their whole body over the rope while sitting on the floor. They even use each other as the jumprope, with 2 girls swinging a 3rd girl as the rope while another girl leaps over her! The group started more than 20 years ago, with hundreds of girls in grades 4 through 8 jumping into the act.
Wee ones: If 2 girls hold another friend sideways as a jumprope, and another Firecracker jumps over her, how many girls are part of the act?
Little kids: If 3 girls jump a rope together, how many jumping feet do they have? Bonus: If a Firecracker has done 7 crisscross jumps so far, how many more does she need to reach 10?
Big kids: If 2 girls hop on their butts to get over the rope, and they each have 10 girls behind them jumping “normally” on their feet, how many girls are in the act? Bonus: If 40 girls line up on the floor and every 3rd one does a cartwheel through a rope, what’s the biggest number of girls who get to do the trick?
The sky’s the limit: If every 4th girl (starting with the 4th) gets to jumprope sitting down, every 6th girl (starting with the 6th) somersaults, and every 8th girl (starting with the 8th) jumps rope on her hands, what number girl is the first to do all 3 tricks?
Wee ones: 4 girls.
Little kids: 6 feet. Bonus: 3 more jumps.
Big kids: 22 girls. Bonus: 14 girls. You’d have 13 if the 3rd, 6th, 9th and so on did it, up to 39. But if the very 1st girl is the 1st and then you have the 4th, 7th, 10th…you’ll have 13 girls at 37, and then the 40th girl makes 14.
The sky’s the limit: The 24th girl. You don’t need to multiply 4 x 6 x 8, because all multiples of 8 are also multiples of 4!
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.