Yes, a school in Canada banned cartwheels. What's worst about this is the school's reasoning:

Cartwheels have been banned at M.T. Davidson Public School in Callander. Cartwheels are not permitted on school property in the playground rules section of the school's draft handbook for 2017-18. The rule came into effect this school year even though injuries have not been reported, principal Todd Gribbon admitted. "The activity can cause concussions, and neck and wrist injuries," he said.

True—any activity, including a cartwheel, can cause injury. Walking down the stairs can cause falls resulting in concussions, neck, and wrist injuries. Walking outside can get you hit by a car. Swimmers can drown. Bakers can catch their hair on fire. Those brave enough to consume solid food can choke. Students sitting still too long can get embolisms.

The precautionary principle—why do something that could cause harm?—seems prudent until you realize it often doesn't distinguish between a calculated risk and what if something terrible happens? Recall that just the other day, a New York Times reporter said it was a bad idea for a kid to mow a lawn, even if it's the White House lawn, because there could be an accident. Really, we are idiots when it comes to risk. We think that there's risk vs. no risk—so why would any ever choose the former?

In the real world, it's always risk vs. other risk. The risk of walking to school seems too great to many people, who forget there's a risk in being driven. There's a risk in doing cartwheels that is offset by the risk of not doing cartwheels. Kids playing, loving the outside, running around, being active, learning balance—all aspects of cartwheeling—may heighten their risk of wrist injuries while lowering their risk of obesity, heart disease, and school-hating-syndrome. The risk of learning to take a risk decreases the crippling fear of risks. The crippling fear of risks (also known as "insurance brain") leads to faulty risk assessments.

Which leads to no carthwheels.