One of Me is Missing

To fourteen-year-old Sally Knox, the world is a buffet of fascinating things to do and learn. She wants it all: martial arts, theater, sculpture, cooking, robotics, music, computer science - you name it!
So, what happens when she gets her wish to be in enough places at once to take all the summer school classes she wants? Complications are just the beginning - before the end, one of her goes missing and the rest must come to the rescue or be trapped forever in their multitudinous state.