DD is I'm y12 she is doing the standard 4 AS levels and has 2 teachers for each.In one subject she is getting solid A grades with one teacher and consistently getting 20 percent scores with the other.I do not think a gap this wide and this consistent can be down to anything except crap teaching.Cousins at school also think she is poor.we are in an affluent area and I think the problem is disguised a lot by tutoring