The sad thing is that some of the most dangerous playground toys also induced superb play. Remember the see-saw? I used to spend hours at my Canadian cottage playing on my uncle's massive, 12-foot-long see-saw. Seesaws were the best training in basic physics you could possibly imagine, because you could scoot up and down the seesaw to figure out where precisely you needed to sit to be able to counterbalance a lighter child. Or you could stack a bunch of smaller kids on one side and see how much bigger a kid you could lift in the air. You learned, in essence, Archimedes' insight about lever dynamics: "Give me a lever long enough and a fulcrum on which to place it, and I shall move the world."Link
But you can't find a single seesaw anywhere in New York any more, because there's no way they could survive liability claims. Sure, seesaws are a superb mechanism for producing the sort of veritiginous play that ludologist Roger Caillois called "illinx" -- the act of voluntarily and joyfully discombobulating your senses. But any activity that produces illinx eventually produces physical injuries, too, and there are more lawyers than taxis in Manhattan.