The Un-Tippable Chair

You already know how to put tennis balls on the bottoms of chairs to keep them from squealing and screeching all the time. 

Now someone's invented an un-tippable chair to keep kids from leaning back and thwapping their little noggins on the floor when they fall over. 

It's a new alternative to making kids sit on the floor, trying to get everyone's attention back when they're laughing at a classmate who's fallen, or taking a student to the office when they really get hurt.