How does a school patrol officer signal for vehicles to stop?

A school patrol officer signals for vehicles to stop by holding up a stop sign. This method is effective because it is a universally recognized symbol for stopping and is visible from a distance, ensuring that drivers can clearly see the command to bring their vehicle to a halt. The use of a stop sign provides a clear and authoritative visual cue, which is crucial in a school environment where children may be crossing the road.

In contrast, waving hands or shouting loudly may not be as effective due to visibility issues or the possibility that drivers might not hear the officer over the noise of traffic. Using a whistle may help to get attention, but it lacks the clarity and universality of a stop sign, which directly communicates the required action to drivers. Therefore, holding up a stop sign is the most reliable and recognized method for a school patrol officer to ensure the safety of children crossing the street.