After telling students to exit at the school, what is the driver's responsibility while the students are stepping off the bus?

AAMVA CDL Manual, Section 10.2.4 – Unloading Procedures at School, p. 10-5 (July 2017 revision); 49 CFR §383.123(a)(1)

Simply opening the door and waiting isn't enough supervision - the manual requires the driver to actively watch each student clear the unloading area before moving on to the next step. This catches problems like a student who trips, hesitates near the bus, or doesn't move away promptly, before the driver proceeds to secure the bus for departure.