"Merging" as in ~25 is the new class size after merge or two classes of ~25 will merge to a new class size of ~50? I never really considered it before but on looking it up it seems some places have average class sizes <20 whereas where I went to school 25-30 was typical so I genuinely don't know which applies in this case.

Even 30 I think worked out towards the later years but, looking back, I have no idea how grade school classes of 25+ held together. 50 would have to be just nuts for all but maybe the final year or two.