A professor requested that I exchange my paper with another student, to get their suggestions. Every student in the course must exchange their papers in this way, before the teacher will look at it. I have never encountered another professor with such a policy and am concerned of the possibility that a student might claim my paper to be their own. What steps can I take to guard against such a possibility?
You could ask the other student to be part of the study. If he/she does some substantial thinking about methods, content, writing etc., you can offer him/her to be co-author.