Final answer:
Motorists should not pass a school bus with flashing lights and extended stop arm from either direction. Without such signals, and unless otherwise indicated by local laws, a motorist may pass at a cautious speed, often not exceeding 10 mph, always ready to stop for children.
Step-by-step explanation:
When a school bus has stopped directly in front of a school to pick up or let off children, the specific rules on whether a motorist may pass and at what speed can vary depending on jurisdiction. However, as a common safety practice, when a school bus is stopped with its lights flashing and stop arm extended, motorists must stop and not attempt to pass from either direction. If the school bus is directly in front of a school but does not have flashing lights or an extended stop arm, and there is no local law stating otherwise, one may pass at a cautious speed which is often not more than 10 miles per hour. It is always critical to approach a stopped school bus with caution and be prepared to stop for loading or unloading children.