All term my DD has been saying she thinks her maths teacher is "rubbish". She doesn't feel he explains things well. However, they have been have been doing algebra (sorry not sure of exact spelling) part of the term, which I suspect isn't easy to pick up. He has been saying things like "you should have been taught x in Year 8, so you'll have to find out how to do it yourselves", and put something on the board last week saying "you are the top set, you can work it out yourselves" - my DD said she hadn't got a clue what to do and sat there all lesson messing about with numbers (although she's confident with friends, she is very quiet with teachers and respectful so in all fairness he wouldn't know at the moment she doesn't speak up to ask things). She was assessed as level 6.75 at the end of last term. This term he's assessed her as level 6 (which must be down the fact she's not understanding what's being taught and expected). She reckons she's about middle in the top set.
DD says she knows of two sets of parents who are going to complain, and I know of another couple who are starting to get negative feedback. I hate the thought of complaining and it may well be the above should be expected in Year 9, but feel I need to say something. How would you go about it?