What should a school bus driver do after stopping the bus and before exiting with pupils on board?

After bringing the bus to a stop and before exiting with students still on board, the bus driver must ensure that the bus is secure. Setting the parking brake is a critical step as it prevents the bus from rolling unexpectedly, which is essential for the safety of the students aboard. Removing the key is equally important because it eliminates any risk of unauthorized use of the vehicle while the driver is attending to the students. This practice is a fundamental safety protocol to protect both the students and the bus itself, ensuring that the bus remains stationary and under the driver’s control.

Opening the door for students would typically happen after the necessary safety measures are in place and before allowing students to exit. Turning off the interior lights could be part of a process to signal that it is time to leave the bus, but it is not as critical as securing the bus. Securing the driver's seat is not a standard protocol that directly relates to the safety of exiting the bus with pupils onboard. Thus, the correct procedure emphasizes securing the vehicle effectively.