Tracking XP Points
I assign students 50 XP points per week on Duolingo. Is there a way to make it so that students can't receive XP points for a lesson that they already completed (multiple times...)? I have students completing the same lesson over and over again and getting points for it. Any pointers?
I think the short answer is that XP assignments are a bad idea, precisely because of the behaviour you've seen.
The skills assignments can be used to get your students to reach a particular point in the tree.
What you really need to to be able to see whether the students' trees are gold or not. Duolingo for Schools doesn't offer that as yet, though.