My primary school had a concrete playground without any trees, and school policy forbid us from running (so we wouldn't hurt ourselves), from playing games like tag (so we wouldn't run) or clapping each other's hands (because we could hurt ourselves). We also couldn't play card games to protect against gambling, nor gather in a group of 5 or more people for some reason. I would have loved a cellphone or anything not to be bored out of my mind during break, but that wouldn't be necessary with a more reasonable school policy.