" Mr. Crossley suddenly wondered why he was why he was worrying about the note. It was only a joke, after all. He cleared his throat. Everyone looked up hopefully. 'Somebody,' said Mr. Crossley, 'seems to have sent me a Halloween message.' And he read out the note: 'SOMEONE IN THIS CLASS IS A WITCH.'
6B thought this was splendid news. Hands shot up all over the room like a bed of beansprouts.
'It's me, Mr. Crossley!'
'Mr. Crossley, I'm the witch!'
'Can I be the witch, Mr. Crossley?'
'Me, Mr. Crossley, me, me, me! "

― Diana Wynne Jones , Witch Week (Chrestomanci, #3)