クラスが終わった後に or クラスの後に

Hello everyone,

I came upon a certain contradiction in one of my journal corrections. I was attempting to express, "After class, ..." in one of my journals. I wrote down,

クラスの後に,....

I was told that it was incorrect and should include 終わった.
I changed it to,

クラスが終わった後に

but was then corrected by another individual saying that クラスの後に was indeed correct. I'm now stuck in a conundrum and can't decided which is correct.

This also begs the question, which would be correct,

朝ごはんの後に or 朝ごはんが終わった後に?

Thank you,
Kai.

PS: I've noticed that some individuals use は instead of に. Wouldn't に be correct as your are indicating a certain time? Before class, before breakfast, before school?

の後（に） is correct. が終わった後（に） is also correct, of course. The problem is on クラス. It's understandable but 授業 is more common (授業の後（に）, 授業が終わった後（に）).
に is not always necessary, as I wrote it in parentheses.

As for は, it's the topicalization of に.

I would get corrected by my teacher for saying 授業 believe it or not. He wanted me to use 片仮名 whenever possible. I think to make it easier for other students who weren't studying as much as I was or something. Anyone else get that from their teacher?

However I agree that 授業 is probably better unless your teacher wants you to use specific vocabulary. I have been corrected on lang-8 for that too.

I do think that クラスtends to create an ambiguity. Even though the context makes it obvious, I've seen the word being used towards "Classrooms" a bit more than "classes"