Interesting. Our seven kids attended a Catholic parochial grade school. Parishioners were given first chance to enroll their kids, but non-Catholics could attend. Sunday mass was not an obligation for them or their parents ... but during the week the classes attended one mass and the whole class attended but non-Catholics did not have to participate in the liturgy. Catholic students served as altar servers or did the readings from the Bible.

Most non-Catholics sent kids because they felt the education was better and/or the presence of moral teachings would be better than what they could expect at the public schools. (That was the perception ... not necessarily the truth. The local public schools are considered among very, very good.) Friends whose kids attend a Lutheran grade school suggested similar requirements or expectations.