How often should school bus drivers practice evacuation drills?

Evacuation drills are typically conducted at least twice yearly in most school districts, often once at the start of the school year and once at mid-year. Students learn the procedure: where the emergency exits are, how to evacuate quickly and orderly, where to assemble after exiting. Drivers practice managing the evacuation, conducting head counts, and communicating with first responders. State requirements vary; some states require quarterly drills. The principle is that an evacuation procedure rehearsed under calm conditions can be executed effectively under stress; a procedure only ever discussed is much harder to execute when smoke fills the cabin.