You're right, canonical link element is meant for duplicate (or very nearly duplicate) content, so not the right approach here. In fact, Google would likely ignore a canonical because it's not duplicate.
A better approach might be to treat these assignments as paginated content, and use pagination markup. In short, this:
- identifies the pages as parts of an ordered sequence
- asks to Google to treat them as a single whole
- and will generally direct search traffic to the first page (unless an inner page is a better result for the user's query)
Here's a blog post from Google covering use cases and behaviour in more detail.