When you visit a zoo, you know you might see birds or swinging monkeys over your head. But having a TIGER up there is a whole other story. The Big Cat Crossing at the Philadelphia Zoo is a see-through bridge that lets tigers and lions walk right over visitors’ heads! The bridge gives the big cats some exercise and a change of scenery so they have a more interesting life. Of course, it’s exciting for the visitors, too. The question is, what happens if that tiger needs to pee while up there? You had better get out of the way!
Wee ones: Counting from the left, which bridge hoop is the tiger walking through in the photo?
Little kids: If 2 tigers stroll across the bridge, how many paws do they have? Bonus: The tiger’s closest cousins are the lion, the leopard and the jaguar. If you have 1 of each big cat, including the tiger, how many fuzzy ears do they have all together?
Big kids: If a tiger’s body is 11 feet long with a 2-foot tail after that, and 3 tigers cross the bridge walking nose to tail, how long is that tiger chain? Bonus: If a tiger, lion, leopard and jaguar all want to cross the bridge in any order, in how many orders can they do that? (Assume they’re one behind the other, not in pairs.)
Wee ones: The 4th hoop.
Little kids: 8 paws. Bonus: Also 8, because 2 x 4 is the same as 4 x 2!
Big kids: 39 feet. Bonus: In 24 orders: for each animal that goes first, there are 3 choices that could go second (giving us 4×3), and then for each of those pairs there are 2 choices for the third spot (giving us 4x3x2) and then the last is decided. So it’s 4x3x2x1, or 24 orders.
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.