Do American children play in school?

I ask this question because I saw a commercial on tv advising parents to do everything they can to get their kids to be more active and participate in physical activity. In the commercial they showed a little girl asking her mother where her toy was and the mother eventhough she has it lies to her daughter and tells her to look in different parts of the house causing the girl to run from room to room thus exercising. To me this paints a picture that American children are so inactive that parents must do whatever possible for them to be active which to me is very strange. I can understand children not being active at home because there are so much other things to do like watch tv, play video games , surf the internet etc. but at school the main way of entertaining yourself is physical activity. I remember as a kid I would be waiting impatiently for the bell to ring for recess or lunch or for school to finish so I can play and run like crazy. There was also physical education which was mandatory .