I sent my two sons (one year apart in age) to a Baptist school. They started in grades K and 1 respectively and attended for two years. We moved and it was no longer practical to send them there so we enrolled them in public school where they spent an entire school year going over things they had already learned at the Baptist school.
I suspect the experience would have been the same at almost any religious school and probably they get farther and farther ahead the longer they stay there.
I remember their disappointment to learn that they wouldn't have a Spanish class in their new school after having had two years of it at the Church school.
Greetings, Graybeard58!
I attended Catholic high school myself; very advanced curriculum, long days, lots of electives. Heck, I even skipped lunch twice a week to attend an elective art class!
Spent one year of business school and two years of college never cracking a book. I didn't need to. I had learned it already in high school.
Great school, great teachers, great principal. I'm a fan of religious education, despite all the pathetic movies Hollywood puts out bashing it. Made all the difference for me!