For a tomboy like me, a sex-segregated all-girl classroom probably would have been miserable.
I would have welcomed a girls only gym class.
why? because you think the girls would be prissy and girly? hardly. the girls at my daughters h.s. were super-competive, in academics as well as sports.
Nonsense. I went to an all girls prep school. Almost everyone I knew who went to Catholic high schools went to single sex schools. The tomboys, the nerds, the Barbie-dolls, all did well. I don't understand this aversion to single sex schools. Especially at the high school level, girls in single sex schools don't have the boys to worry about and it allows them to concentrate on their school work, activities, and to have leadership positions they might not have (or they might not want because of how they want to appear before the boys) in a coed environment.
As for boys, 4 years with the Jesuits (who aren't afraid to use corporal punishment) or in a Christian Brothers school will keep most boys on the straight and narrow.
The idea that kids in single sex schools won't know how to interact with the opposite sex doesn't make sense. People have brothers and sisters, kids go to camp, Sunday school, etc. and have plenty of opportunities to interact with the opposite sex.
What they are in school to do is to learn and study. Taking away the immediate distractions of the opposite sex, especially at the high school level, allows them to do that.
I have two girls; an all girl class would have been heaven for my older daughter as she was often frustrated by boys and their need for constant movement and fidgeting. My younger would have hated it as she thrived in environments that were typically male dominated. She LIKES competing against boys. Yes, there are a few competitive girls, but very few that are as hard-edged as she is when it comes to grades and learning. She fits in better with boys.
Not sure how a class would be designed around those facts, or if one should be. Maybe it is better to be around the opposite sex to rub the rough edges off of personalities.