The Only Thing Worse Than Witches (Dial, August 2014) is an excellent bet.
In a small town by the sea lives a community of witches. Not particularly nice witches, the sort that the local non-witches are somewhat nervous about, but not, generally speaking, horrible.
There are exceptions. And one of the worst of these exceptions is moonlighting as a teacher.
Rupert, one of her unfortunate students, just thinks she's the most abominable horrible thing ever to happen to him (and why won't the adults believe their kids when they say so?). But then Rupert meets a girl his own age--a girl who's a witch in training. And Witchling Two opens his eyes, breaking the rules to share witchy knowledge with him. Witchling Two picked Rupert to be her apprentice--she needs a study buddy to pass her witch exams. Rupert (forbidden by his evil teacher to socialize with his classmates) is happy to have a new friend.
Witchling Two's chances of passing her exams aren't looking good--her spells keep going bad. Rupert's chances of escaping his teacher aren't looking good either--her spells work just fine! But the two of them together figure out a way to come up on top, and all works out very nicely indeed.
The friendship between Rupert and Witchling Two is satisfying, and her struggles with magic convincing; there is a backstory to Rupert's mothers more than usual anxiety viz the witches that adds some depth to the story, there's some ambiguity about two the witches that's very nice, and the plot wraps up nicely. And Rupert's teacher is beautifully over the top in the horror that constitutes her approach to educating/terrorizing the young.
So like I said above, this is a fun one for the elementary school reader. If they like the cover, they will like the book. And you'll know if you are the type who'll enjoy it lots if you don't flinch when you learn that there is a teacher named Miss Snugglybuns (not Rupert's teacher!) because it is the sort of lighthearted, whimsical sort of story in which nice teachers are named things like Snugglybuns, but even though I found this off-putting, I was able to read the book in an appreciative spirit.
In short, what it sets out to do it does well.