From a blog post by preschool teacher Tom Hobson (AKA Teacher Tom) on the importance of play in learning:
"I'm so happy to live in a world in which I don't need to defend the educational benefits of turquoise water, wooden boats, chop sticks, clothes pins, and rocks."
Of course, you may reasonably be wondering, "What kind of school does does this guy work at that he doesn't have to defend the educational benefits of playing with wooden boats in turquoise water?" This kind apparently. And he's the school's only employee. That probably helps.