I'm trying to figure out a way to have a category of assignments that students can pick and choose from.

I use weighted averages (in percentages) with assignment categories.

My goal is to have a category for Enrichment Assignments (extra readings, attending and reflecting on relevant campus events, meeting with a research librarian, etc.) that vary in point values (from 1 to 3 points per assignment), and then students have to complete 10 points worth of assignments in the category to complete the corresponding 10% of the course grade. 

Is there a way to set up this category so that they are not losing points for the ones that they decide not to do, but are getting points for the ones that they do decide to do?

Thanks!