What is the primary purpose of a school bus stop sign?

The primary purpose of a school bus stop sign is to stop all traffic to ensure student safety. When the stop sign extends from the side of a school bus, it signals drivers approaching from both directions that they must come to a complete stop. This is crucial because it provides a safe environment for students who are getting on or off the bus. The extended stop sign serves as a visual indicator that children may be crossing the street or getting on the bus, and stopping all traffic reduces the risk of accidents or injuries during this critical time when students are most vulnerable.

While the other options touch on aspects related to bus safety, they do not capture the essential function of the stop sign. For example, indicating when to speed up or reminding students about the bus schedule does not address the immediate safety needs of students getting on or off the bus. Knowing this importance helps drivers remain aware and diligent when approaching a school bus equipped with a stop sign, reinforcing the need for caution around school transportation zones.