Upvoting of annotations

[jeremydean]

All three major competitors have "upvoting" on annotations.

Upvoting could be argued to add an additional way for students to interact with each other/each other's content.

Several competitors also enable sorting by upvotes to help students and instructors to surface the most valuable or relevant annotations.

Upvotes are also sometimes used as a component of grading as in Perusall.