My D18 did (regular) physics in sophomore year of high school. The previous physics teacher had left at the last minute so they had a biology teacher who told the kids at the start of the year she was 2-3 classes ahead of them in learning the material. We complained to the principal but were told no one else was available. So very little learning happened, but there were plenty of As in the class, since the teacher already knew the parents were on the warpath.