Sounds like liberals ran your Catholic school. In public grade school, we had one class where the teacher said Islam spread by the sword.
My very Catholic aunt gave me (actually all the kids in my family) an illustrated book on the Crusades. I read if for pagentry and pictures, it was very, very interesting. However, in religion class the approach to Islam was fairly neutral, even though there seemed to be a lot of remorse about all the lost Christian shrines. In history class, they taught about conversion by the sword, but made it seem archaic, ancient history, like, “Who remembers that any more?”