If it works well, is it ethical for a teacher to let you do it as an exercise (simplest example: some of those doing the exercise may be in a relationship with someone not in the class)?
We didn't do the full procedure, just a subset of the questions. We were not forming intimate relationships, just developing a sense of closeness in a short amount of time and learning about what that involves (e.g. reciprocal personal self-disclosure). So I don't think it was harmful or unethical.