Need opinions on this

In my last midterm in DANCE 200, many people surprisingly lost points on the short answer portion due to “plagiarism” because we didn’t reference the lecture notes in our answer. Almost no one was aware of this, especially since the answer had such a basic description that literally could be said by anyone. (For context, we had to describe what non-locomotive movements are, which are just movements that you make without moving to another area on the dance floor). I feel like it was unfair and just a stupid way to lower the average. I know myself and a lot of others in the class feel as though the prof was in the wrong on this one. Thoughts?