Many classes have smart boards, the school have a large auditorium, they have plenty of TVs, so it is not a question of logistics but the reason was that they didn't want "to bring politics in the school".
I guess they haven't understood that it is more an historical moment than just celebrating one party elected.This is the French view of things.In the US, when a President is elected, everybody is for him and try to help him. In France, as soon as someone is elected, the media or the opposite party is trying to destroy him. I'd love to receive your comments on that !
Anyway, some parents pulled out their kids out of the school for 2 hours, so they could see the whole event.