What must happen first when a school bus driver prepares to stop for loading or unloading children?

When a school bus driver prepares to stop for loading or unloading children, the first action is for the amber lights at the top of the bus to flash. This serves as a warning to other drivers that the bus is about to come to a stop. The amber lights act as a caution signal, indicating that drivers should start to slow down and prepare to stop for the bus.

This initial step is crucial for enhancing safety; it alerts both the vehicles behind the bus and those approaching from the opposite direction that children will soon be boarding or disembarking. Following the activation of the amber lights, the driver will then fully stop the bus, at which point the red lights will flash, and the stop arm will extend to ensure that all traffic comes to a halt before children can safely enter or exit the bus.