What should you observe when a school bus begins to stop?

When a school bus begins to stop, observing that its lights may start blinking is crucial because this is a primary indication to drivers that the bus is preparing to make a stop and that students will be getting on or off. The blinking lights serve as a warning signal to ensure that nearby vehicles are aware of the situation and can prepare to stop as well, thus enhancing the safety of children around the bus.

Additionally, the extending stop sign and further safety measures typically accompany this warning. However, the specific initial observation to look for in relation to the bus's stopping process is the activation of its blinking lights, which is a standardized protocol designed to alert motorists. The other aspects, like the bus being parked or reversing, do not align with the typical stopping procedure of the bus and could present a danger if incorrectly assumed.