The room you teach in
Most of a teacher's day is spent in one room. Most of what goes wrong in that room is shaped by things nobody decided on purpose: where the desks ended up, which door is locked, where the broken chair was left. 🏫
A classroom risk assessment is a deliberate look at that room before something happens. It asks: if a fight broke out, a learner became aggressive, or we had to get out fast, would this room help us or trap us?
You cannot fix overcrowding on your own. But you can usually make the same room noticeably safer with the furniture and rules you already have.