At the community college where I work, we are instructed to give feedback to students via the sandwich technique. That is, sandwich your negative feedback in between comments on what the student did well.
To me this seems a little silly, and overprotective of egos, but a lot of my students have never been told they did anything well, ever, and so I do get that positive reinforcement may motivate them. However, I fear that they may just skip over the bad and keep only the good.
And sometimes, I can't think of two nice things to say. When a student has failed on every level of the assignment, how do I proceed? "You spelled your name right, nice work! You did not follow assignment directions, misunderstood the fundamental point of the assignment, clearly did not do the readings, and did not use terms correctly. You also didn't cite your sources or meet the minimum word count. However, you did turn this assignment in only two days late! Great improvement!"
How do you even grade a student who turns in a paper containing this sentence:
Even though, they are target at black, helping improve legal, social, and economics of the blacks, but they help all cultural.*
This is a native English speaker with at least a G.E.D.
My comments to this student began: "your assignment concerns me."
*paraphrased as best I could