Final answer:
A school zone sign with flashing lights and a posted speed indicates the need to slow down to 20 mph in a school zone for student safety. These signs and traffic signals are crucial for pedestrian safety and help manage vehicle speed.
Step-by-step explanation:
The sign that indicates a school zone where you must reduce your speed to 20 mph or less when the light is flashing is typically a school zone sign with flashing lights and/or a posted speed limit during certain hours.
These signs are critical for pedestrian safety, especially in areas where many students are coming to or leaving campus. It's important for drivers to adhere to the speed limit indicated by these signs to prevent accidents and ensure the safety of students. Traffic signals also play a vital role by providing specific times for pedestrians to cross, therefore reducing the need for them to dodge traffic.