What kinds of rules do most schools have?

Well, most schools have pretty standard rules about attendance and uniforms - that's the basics. But what really sticks in my mind from my high school in Hangzhou was how strict they were about mobile phones. We had to hand them in every morning and only got them back after class. The reasoning was obvious - to minimize distractions during lessons. Honestly, it worked pretty well for focused learning, though sometimes it felt a bit extreme when we needed to contact parents urgently. These days I notice Shanghai schools seem more flexible, allowing phones for educational apps but still limiting social media use during class hours.