What is a school bus driver required to do at most railroad-highway crossings, regardless of whether a train is visible?

Correct answer to question 5 (School Bus): Stop, open the door and window to look and listen, then proceed only when it is safe

Why

Stopping and opening the door and window lets the driver see and hear an approaching train that might not be obvious from inside a closed bus, which is why this step is required at most crossings even with no train in sight.