Mr. Merlin, a wizard disguised as a substitute teacher, magically transports two fifth graders to a fairyland where they must solve a riddle to find out who has stolen the seven dwarfs' bag of diamonds.
William E. Brittain was an American writer. He is best known for work set in the fictional New England village of Coven Tree, including The Wish Giver, a Newbery Honor Book. Brittain was born in Rochester, New York. He decided he wanted to be a 5th-grade teacher, and in addition to teaching, used to read stories in mystery magazines. After some time, he decided he could do as good a job at writing as some of the authors he read; he got coaching on writing from Frederic Dannay of Ellery Queen's Mystery Magazine (in which, along with Alfred Hitchcock's Mystery Magazine, most of his mystery stories were published). He wrote two serials from 1964 to 1983, as well as other stories, before moving on to the children's books for which he is better known. Brittain is also the author of the popular book All the Money in the World, which was adapted as a 1983 movie.
This book unsuccessfully disguises the fact that it's a math instruction book. The story starts too quickly with a sub-teacher who is "really" Merlin and transports 2 students in fairytale land - the whole adventure and mini-math riddle falls flat on its face. Not worth reading . . .
The shortest of Bill Brittain's books I think. Supposed to be a real short story on a mesh of fairy tales, turned into a single adventure. There's imagination at play, but it seemed more directed to young children than people actively looking for entertainment.