The single biggest cause of broken kids glasses isn't the fall, the football, or the wrestling match. It's a backpack. Specifically: glasses left loose inside a bag where they get sat on, bent, and scratched by everything else inside.
Habit one: always use the case. We know, we know. But the case keeps the frame from twisting. Most of our frames can survive a 2-metre fall onto concrete. They cannot survive a 60-kilogram parent sitting on a backpack.
Habit two: teach the two-hand rule for putting them on and taking them off. One-handed glasses removal twists the frame asymmetrically over thousands of repetitions. Two hands keep it aligned.
Habit three: clean with the cloth, not the shirt. Shirts carry small particles that scratch lenses. The microfibre cloth that ships with the frame is all you need.
Habit four: don't leave them on a car dashboard. Heat warps plastic frames. Even TR-90 has limits in direct sunlight inside a car on a summer day.
Habit five: store upside down when not in the case. It sounds counterintuitive, but frames stored right-side up on a flat surface gradually loosen the hinge tension over time. Upside down distributes the weight differently.