I hated gym class and never did well in it because I was this little fat kid who didn't want to put any effort into getting any sort of physical exercise whatsoever. In fact, I had "exercise induced asthma" (although looking back, I think it was just me being vastly overweight and out of shape) and used to pretend it was worse than it actually was to get out of running. I know, it's horrible, but I was young. :x
I didn't end up getting physically active and in shape until I left high school, as a matter of fact. Now, I love going to the gym. XD Funny how that works.
Sex Ed was so awkward in elementary school because we could tell our teachers were uncomfortable teaching it so it didn't create a very comforting learning environment for such a subject. In high school, it was grouped with gym and our gym classes were single-sex classes, so I was only with girls. It was so much less awkward, not because it was all girls, but because the teachers didn't make it awkward at all.
Thank god I only had to do gym up to grade nine, though.