I went to a catholic school. Everyone was catholic We did not have any muslims there. What is wrong with these people?
Catholic schools now typically have many faiths attending; however, I don't know of any atheist students. The Catholic schools in my area have Muslim and Hindu students (there are very few Jewish people around here or I'm sure we'd have some of them), in addition to the Catholics. The Muslim and Hindu students are almost exclusively the offspring of local physicians.
At the local Catholic high school all students, AFAIK, attend Mass, but the Muslim students do go to a room to pray separately -- it is just a plain room -- nothing fancy or tailored to them.
All students are exposed to Catholic doctrine and values but those who are not Catholic are not required to adopt the Catholic faith.