nouns - What's the correct unit for homework?

Consider the case when a teacher has thirty students in the class. The noun "homework" is uncountable so he cannot say "I have thirty homeworks to grade every week." My question is that if there is any unit of homework so that the sentence "I have thirty (units) of homework to grade every week" can be valid?

Edit:

1. After reading the replies, I think I should make the situation more clear. I myself am a math TA. What our students need to do for homework is usually about ten exercises from the textbook. I feel if I ask another TA how much homework he needs to grade, the usual reply will be like, "I have two sections, fifteen students each, and we have one assignment every week." Since the amount of exercises is usually the same, we don't really care about it. The amount of homework to grade mainly depends on how many students we have. But I always feel this kind of reply to be very indirect. So my precisely question is if there is any way to reply the question "how much homework do you need to grade?" by saying "I need to grade thirty (units) homework every week."


2. Based on what I see from the replies, I have the impression that different countries have different answers for this question. Is this true? I'm on the west coast of the US so the way in which people there answer this question is what I care about the most. But I'm still interested in knowing the difference.

Answer

In your example, you could use pieces, as in I have thirty pieces of homework to grade every week.

piece noun [ C ] (THING)
a single object of a particular type:
a piece of furniture/clothing/equipment

a piece of paper (= a whole sheet)
a piece of china (= an object made of china)
a piece of information/advice
(Cambridge Dictionary)

However, that doesn't seem particularly idiomatic to me. You could use assignments, as in homework assignments:

assignment
noun [ C/U ]
us ​ /əˈsɑɪn·mənt/

a particular job or responsibility given to you:
[C] The homework assignment was to read Chapter 2 in our history book.
(Cambridge Dictionary)

However, in my experience, it's more common to use the type of assignment instead of homework. I think the most broad term is assignment, but you could be more specific:
I have 30 ______ to grade every week.

• assignments


• papers


• essays



• worksheets


• modules


• warm-ups


• tests


• quizzes


• etc.

---

Edit:

I was very briefly a grader (or, "reader") in a related field. I can't remember exactly how I talked about it, but if someone asked me, "How much homework do you need to grade?", I would probably reply

I need to grade thirty [assignments] every week.

You could also say sets (as others have mentioned), or even submissions (more generic). I'm thinking maybe even "papers", but that's usually used with reports or essay-like works.

I don't think I would have responded in the form you supplied, "I need to grade thirty (units) homework every week." But, that's just my personal feeling of it. You can still use pieces, as mentioned earlier. It may or may not sound slightly strange to the listener, but you will be understood.

To my surprise, BrE users are reporting that pieces of homework is idiomatic to them. I did a little Ngram search, and it appears that the phrase is more common in BrE.

I'm from the West Coast (US).