When ghost kids Bianca, Salem and Hester are chatting away in the classroom about a great ghost book they have read, they think no one can hear them because they are whispering. But when they see the chalk on the blackboard writing as if by itself "Stop Talking in Class" they are terrified. Then the chalk writes or the blackboard, "If you want a really good book to talk about, then bring it into class and we'll read it together!"

Headmaster Öst comes into the classroom and says to the students, "Don't be alarmed. your teacher for Reading is Mrs Graves. She's a very good teacher. The only thing you have to remember about her is that she is invisible!"

The girls decide that they really want to know why she is invisible, what she looks like, does she wear make up? Is she beautiful like a princess, or ugly like a monster?

The chalk writes on the blackboard, "heard that! it should not matter what I look like. How I look should not affect your respect for your teacher. What anybody looks like should not affect the way you look at them."

The girls know this is true. But it doesn't stop them wondering and trying to guess what Mrs Graves looks like - but without her hearing them!