Merlin's Apprentice by Tanya Landman
The exciting sequel to Waking Merlin, a fantasy adventure set in the modern day. It's Katrina Picket's birthday, and not only has her favourite bear been burnt to a crisp, but her best friend's ignoring her, and the supply teacher is none other than Morgan le Fay, the most evil sorceress that ever lived! Katrina summons Merlin. But can he train her to become a sorceress in time to defeat Morgan and save the country from destruction?