Can I watch movies with nudity for a class?

It depends, but you should avoid the nude or sexual scenes even when a film is set for class. Islam asks you to lower your gaze, and a homework label doesn't change that. In practice you can usually watch the rest of the film, skip the scenes, and ask your teacher about alternatives.

Lowering the gaze still applies

Allah tells believers to guard their eyes:

قُل لِّلْمُؤْمِنِينَ يَغُضُّوا۟ مِنْ أَبْصَـٰرِهِمْ وَيَحْفَظُوا۟ فُرُوجَهُمْ "Tell the believing men to reduce [some] of their vision and guard their private parts." Quran 24:30

The next verse gives the same command to believing women. When the Prophet ﷺ was asked about a sudden, unintended glance, he told the Companion to turn his eyes away (Sahih Muslim 2159). Deliberately watching nudity or sex scenes goes against this, whether it's for entertainment or a course.

What you can usually do

Check first: sites like IMDb's Parents Guide or Common Sense Media list nudity scene by scene.
Watch on your own copy where you can, and skip or look away during those scenes. You'll still follow the story.
Read a summary of the skipped scene so you don't miss anything the essay needs.
In a screening, sit near the end of a row, look down or step out briefly.

Talk to your teacher or lecturer

Most teachers in the UK, Europe and the USA are used to students with religious or personal reasons to avoid explicit content. Ask politely and early: "For religious reasons I avoid nudity on screen. Could I skip those scenes, or is there another film I could write about?" Many will agree, especially when the film is one of several options. If the course is film studies or media studies, look at the reading list before you enrol. See Can I choose any major as a Muslim? and Can I study music or fine arts at university as a Muslim?

Where scholars allow more

Scholars allow looking at the body when there's a real need, such as a doctor examining a patient or a medical student learning anatomy. A literature or film class rarely meets that level of need, because you can understand the plot without the explicit scenes. If you truly can't pass a required module without it, ask a knowledgeable local scholar about your exact case.

Be gentle with yourself

If a scene appears suddenly, the first unplanned glance isn't held against you; just look away. Don't let one awkward screening make you feel like a bad Muslim. The same balance applies to films in general; see Can I still watch horror movies as a Muslim?

Key points

Lowering the gaze applies to class films too.
You can usually watch the film but skip the explicit scenes.
Ask your teacher early about skipping scenes or another title.
Real necessity, like medical training, is judged differently.

Tip: Save a short, polite email template about explicit content and send it at the start of each term. Asking early is much easier than walking out of a screening.