A playground with seesaws, swings, and jungle gyms is already pretty fun. But mix In some real airplanes and 10-story-tall slides, and things get really exciting. This playground in St. Louis covers 600,000 square feet right in the middle of the city. It has not 1 but 2 of those super-tall slides, two airplanes, and a bus that hangs over the edge of a roof to make it scarier. Visitors can also crawl through hundreds of feet of tunnels, or chuck balls at each other in the ball pit. The playground was built in 1997 by artist Bob Cassilly, but so far so good: the bus has stayed up there on that roof.

*Wee ones:* If the playground has 2 planes and a school bus, how many surprise vehicles does it have?

*Little kids:* If you slide down the 10-story slide and start screaming just after sliding down 2 stories, how many stories do you have left to slide and scream? *Bonus:* If the planes are 50 feet off the ground and the bus is 20 feet higher, how high up is that bus?

*Big kids:* If the giant ball pit has 20 blue balls, twice as many red balls as blue, and twice as many green balls as red, how many more green balls than blue does it have? *Bonus: *If 32 kids board the bus and it can hold triple that without falling off the roof, how many more kids can climb in?

Answers:

*Wee ones:* 3 vehicles.

*Little kids:* 8 more stories. *Bonus:* 70 feet.

*Big kids:* 60 more green balls, since there are 80 of them. *Bonus: *64 more kids, since it can hold 96.