Is PE class set by grade?

I mean as in all 1st years go to PE class then they all go back to class. Or do they send SOME 1st year classes to PE and in the same day, send the rest of the 1st years? Or how exactly does their PE schedule work?

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Answer:
It is all depend on the school capacity and timetable.
My kid school is small, 2 classes per grade. So for PE, depends on what lesson of PE.
Lesson that require gym or school ground usage, can be either separate or together.
Class based PE lesson are mostly separate.

Yes, it depends on the school. But most schools, from elementary to senior high, has homeroom classes, and each homeroom class typically has their own timetable. It's the same for PE. So, one homeroom class would have Physical Education class together, instead of a whole grade taking it together.