Last year, I went to N elementary school and taught English to the 5th grade students. As warm up, we sang Londonbridge. After that, I said, "Let's make men and female pairs, and dance to the music." The moment I said, students complained, "Eh?", "What?", and"Boo!"one after another. So instead of making men and female pairs, they made pairs with next to him/her.
Why were they reluctant to make these pairs? In a sense, the reason was that they were at the beginning of adolescence. So, they might be ashamed of dancing with the opposite sex.
From this case, I learned that I should have considered their feelings and situations. However, I don't mean to oppose the idea of studying with the opposite sex. It depend on the case.