We don’t have live dinosaurs running around today who could step on a bathroom scale and weigh themselves. But how much DID they weigh? Well, scientists have tried to guess. Take the spinosaurus, which true to its name had huge 5-foot spines along its back. We have only bones to help guess the weight; we don’t know how much skin, fat and muscle this fellow had. We do know these dinos were about 50 feet long, which is longer than most whole houses, and easily stood over 10 feet tall, way taller than your bedroom ceiling. The whole animal could have weighed anywhere from 8 to 23 tons. By comparison, a car weighs about 2 tons. Even if you had a pet spino dino, it couldn’t fit on a bathroom scale anyway!

*Wee ones:* Who’s taller, you or a 5-foot-tall spine on a spinosaurus? Find out your height in feet!

*Little kids:* How *much* taller than you is that 5-foot spine — or how much taller are you? *Bonus: *If you have 10-foot measuring tapes, how many of those would you have to lay end to end to measure that 50-foot dino?

*Big kids:* A 23-ton spinosaurus would weigh almost 3 times an 8-ton one, if that turned out to be right. How much would YOU weigh if you turned out to weigh 3 times as much? *Bonus:* How much more does a 23-ton stegosaurus weigh than a 6-ton elephant, in *pounds*? (Reminder if needed: A ton has 2,000 pounds.)

*The sky’s the limit:* If you have 3 spinosaurus of different sizes, and the first 2 together weigh 11 tons, the 2nd and 3rd together weigh 22 tons, and the 1st and 3rd together weigh 15 tons, how much does each one weigh?

Answers:

*Wee ones:* Different for everyone…see if your height is more or less than 5 feet.

*Little kids:* Different for everyone again…subtract your height from 5, or subtract 5 from your height. *Bonus:* 5 tapes.

*Big kids:* Different again…multiply your weight by 3. You can also add it to itself, then add it on 1 more time. *Bonus:* 34,000 pounds, since it weighs 17 tons more.

*The sky’s the limit:* 2, 9 and 13 tons. If the 1st and 2nd weigh 11 and the 1st and 3rd weigh 15, then swapping out the 2nd dino for the 3rd increased the total by 4 tons. So the 3rd weighs 4 tons more than the 2nd dino. Together those 2 weigh 22 tons, so if the 3rd were as small as the 2nd, they’d weigh just 18 tons. That means the 2nd dino weighs 9 tons, and you can figure out the other 2 from there.

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.