Stranger With My Face (or make jokes that include "insert something wth my face" as a punchline) and Daughters of Eve. Still, I somehow had missed Down a Dark Hall. I set about remedying that immediately.
The word that came to mind several times while reading it was "farfetched". I could hear Amy Poehler's voice in my head saying "REALLY?!" I dislike when parents in novels don't listen to their children, and protagonist Kit Gordy's mother takes the cake. The school is evil, there are only four students, the letters aren't arriving...who is this mother?
Down a Dark Hall would be a good novel to show students the mechanics of writing a novel. It is obvious where Duncan uses foreshadowing and it follows the classic story structure that would make it easy to map on a Freytag's pyramid. Still, it's not a book I will recommend to them as a scary story they've got to read.
Now I am afraid to re-read Daughters of Eve and Stranger With My Face. Boo!