Stop and wait for the school bus to load/unload just as if in a car.
See where the rug rats are heading and take the appropriate action
Keep going, yell at any kids in front of you to get out of the way
There are no school buses where I ride
On my ride yesterday, I went through the TCU campus late at night and the pedestrian light on university tripped for a single person. No problem, but man, that's a long light. So I got off the bike, walked it along the street until I passed the pedestrian crossing, remounted and rode on.
I haven't encountered a school bus while riding in probably 4 years, but I still voted stop, which is what I did the last time it happened and probably what I'll do the next time. Probably because one can never say anything about the future with 100% certainty, but I'd get it a solid 99.7% chance I'll be stopping.