The horribly haunted school
Author: Mahy, Margaret.
Monty is allergic to ghosts; if there's one around, he sneezes. When he discovers a ghost named Lulu haunting his home, his mother sends him away to the Brinsley Codd School for Sensible Thought, where she hopes he will learn that there are no such things as spirits. But Monty has only been inside the school a minute when he starts to sneeze. How can Monty stop believing in ghosts when the school itself turns out to be haunted by the ghost of Brinsley Codd?