Room 9 is a biology classroom. It is tucked away next to Mrs Porteous' office and if you haven't been in the room before it can be quite a struggle to find.
It doesn't have a set teacher and seems to be shared equally between the biology teachers, although at the front of the classroom there is a notice saying 'remind her to do the register' - who is 'her'? We'll never know.
On top of one of the filing cabinets is also an Obama Prism left there presumably by Mr Heald's old form, as he let them make some when it was his birthday.
Room 9 is also one of the more modern science labs, and has much less interesting desks as they are just grey plastic rather than the older science rooms which can offer hours of reading material just from the inscriptions on the wooden benches, making science lessons reasonably more interesting.