One of DD's friend (Y3, 7yo) told DD that she saw someboday was having S-E-X in a car the other day. DD didn't response as she didn't know what SEX means. She asked me what SEX is tonight and I was totally shocked. I can't imagine that a 7yo child talk about sex in the school (or virtually anywhere else). Do I need to talk to the teacher about it? what will the school do to prevent such kind of talking between students?