Is "homework" countable?

Solution 1:

"Homework" is uncountable since it is treated as a general meaning not a particular item, like "work", "money" etc.

In your case, use "assignment" instead.

May I have my last three graded assignments back please?

Solution 2:

While I've seen the word homeworks used, I've never seen anything legitimate to indicate that it's correct. In any case, you can use the term homework assignments to refer to multiple homework items. That's a fairly common term, at least in American English.

Solution 3:

Traditionally, it is not countable, and most dictionaries list it as such.

However, the Merriam-Webster thesaurus (although not the Merriam-Webster dictionary) does have an entry for homeworks. Moreover, the plural form is used by at least some groups of educated native speakers.

One's best bet is to try to find out if one's audience belongs to a group that tends to use homeworks. If yes, then go ahead and use that word yourself. If not, rephrase as homework assignments or something similar.

Discussion

Merriam-Webster Thesaurus

Notice that the Merriam-Webster thesaurus has the following entry:

homeworks noun

plural of homework
Synonyms of homeworks

as in schoolwork

Synonyms & Near Synonyms for homeworks

schoolwork
assignments, lessons, reading
lectures
drills, exercises, practices (also practises)
études, studies

(Interestingly, the Merriam-Webster dictionary entry does not give a plural form for homework.)

Examples of usage by educated native speakers

Such examples are not hard to find at all. For instance, American professors of linguistics, physics, and mathematics, at least, use the word homeworks quite frequently.

All of the examples below are from native speakers, as best as I can tell.

Here are five examples from linguistics professors:

Final grades will be calculated as follows: 30% for homeworks, 20% for the midterm, …
^{Penny Eckert and Ivan A. Sag, Linguistics 1: Introduction to Linguistics (Syllabus), 2011, here.}
Late assignments are not accepted, but your two lowest-scoring homeworks will be dropped.
^{Adam Jardine, Introduction to Linguistic Theory (Honors) (Syllabus), 2018, here.}
Homeworks are due at the beginning of class on the days indicated.
^{Emily M. Bender, Linguistics 461: Introduction to Syntax (Syllabus),here.}
If turned in ​complete​, the homeworks will be graded 8 (well below average), 9 (average), or 10 (well above average​); but 0 if not done.
^{Anthony C. Woodbury, Linguistics 306: Introduction to the study of language (Syllabus),here.}
Homeworks: 25% (lowest score dropped)
^{Dani Byrd and Toby Mintz, Ling 275: Language & Mind (Syllabus), 2006, here.}

Here are five examples from physics professors:

Some homeworks are 'secret' assessment exercises: General GRE, Praxis and Major Field Tests
^{Richard Robinett, Penn State Physics Undergraduate Program Better Practices, 2010, p. 12 here.}
Homeworks are like sports practice
^{Tom Moore , Teaching General Relativity with Tensors, 2006, here.}
These concepts can be introduced to students through labs, homeworks, and discussion questions.
^{Brianna Billingsley and Cory Christenson, Incorporating Non-Western Contributions Into the Intro Physics Curriculum, 2019, here.}
With their flexible design, PhET sims are used in many ways—as demos, homeworks, or inexpensive, accessible lab alternatives—and getting started is easy with our database of over 500 activities.
^{Katherine K. Perkins, Teaching Physics with PhET Simulations: Engaging Students and Increasing Learning (Abstract) 2012, p. 58 here.}
In this talk, we will outline the reforms—including consensus learning goals, “clicker” questions, tutorials, modified homeworks, and more—and present evidence of the effectiveness of these reforms relative to traditional courses.
^{Katherine K. Perkins, Steven Pollock, Stephanie Chasteen, Steve Goldhaber, Rachel Pepper, Michael Dubson, and Paul Beale, Colorado's Transformed Upper-Division E&M and QM courses: Description and Results (Abstract) 2010, p. 119 here.}

And here are five examples from mathematics professors:

Homeworks 1-3
^{David Blecher, here.}
There will be two midterm exams, weekly homeworks, and a final exam.
^{Scott Sutherland, MAT 141: Honors Calculus 1 (syllabus), 2012, here.}
MIT 3.016 Homeworks
^{W. Craig Carter, Mathematics for Materials Science and Engineers, MIT 3.016 (syllabus), 2011, (here). Click on the link 'Problem Sets and Solutions'; you will reach this page, which is where the word homeworks appears (in the page heading).}
Homeworks (41/42 Track); Homeworks (51 Track)
^{Andrew Schultz, SSEA 2006: Mathematics Track, 2006, here.}
All homeworks, except the first one, are due on Thursday at 3:30pm
^{Mike Clancy and David Wagner, CS 70, Spring 2005: Discrete Mathematics for Computer Science, 2005, here.}

In searching for examples, I also saw examples of similar usage by professors of comparative literature, philosophy, computer science, chemistry, and sociology.