A rubric is a small grid of criteria and levels that says, up front, what good work looks like. Sharing it with the assignment helps students aim correctly and helps you grade consistently and faster, since much of the feedback is built into the criteria.

The most useful feedback points to a specific criterion and a next action, for example: your claim is clear, but the evidence does not yet support it, so add a source for each point. Feedback that only assigns praise or blame rarely changes the next attempt. When you can, give feedback while students can still use it, on a draft rather than only on the final.