Feedback for a student showing improvement One of the students whose work I'm grading has just handed in a piece of work which is much better than what I've come to expect of them after several classes. I was just about to write some rather positive comment on their work, along the lines of "Good job! You're doing much better than you used to.", when it struck me that perhaps this is not such a great idea after all.

The problem is that, even after the jump in performance, the student is by far not the brightest in the group (not that they're not bright; the group is simply very strong overall). This leaves me with a couple of possible concerns. Maybe that would be somewhat unfair to the other students, who usually perform at a consistent level. More importantly, this might come across as a backhanded compliment. Something along the lines of "Well done, you are now about average, which is very high, judging by your abilities." (which of course is very far from what I mean to convey). Are these legitimate concerns?

On the other hand, it feels slightly wrong not to acknowledge improvement. And I usually try to leave some kind word next to a particularly good solutions of people at the top of the group.

So, is it a good idea to comment on the fact that student is doing better? If so, how do I make sure I will not be misunderstood?
Just personal opinion + some experience.

First, if it's graded and the grade shows a large jump, then I'd just leave it as is.

Second, perhaps the first homework was not a true reflection of the student's ability (sickness, etc.) Just be mindful but I trust that you have gotten a clear impression of the class by now.

I feel that it's okay to remark on the improvement if the last homework was apparently bad (say, like a fail or near-fail.) Otherwise the student may not even realize it was bad all along, and this "better" comment can be a harsh blow of reality.

My desire to remark will grow stronger if I have written some suggested improvements in the last assignment or highlighted the common errors in class and the students actually followed my advices. My rule is to pair each good remark with a reason, and each bad remark with a suggestion. So, rather than "good job!" I'd suggest "good job on [whatever done right]" in order to reinforce such positive behaviors.

And lastly, just my thought and I expect not everyone would agree with me: I don't think giving customized remark or suggestion is a sign of being unfair. If someone struggles and wants to put in the effort to perform better, I wouldn't mind giving more detailed guidance in my feedback. The important thing I always remind myself is while past records are important, we should be prepared to evaluate our students with fresh eyes as well whenever possible. Don't give the impression that we had already given the final grades in our head after the first couple classes.