Teachers Pet Training

I forgot the author and title of this book! help?

I had a teacher that read us this one book in fifth grade. I can't remember the title of the book our the author! But I do remember some of the details;
It was about children who were trained to be gymnast. They were tricked into thinking that they were in space, and if they didn't learn to be a gymnast (or if they got too old or tall etc...) then they were killed.-Even though they were not in space, they were just tricked.
At one point one of the main characters was not a good gymnast but they kept her anyways as a pet? Like literally as a PET, and her "owners" were like giants?
In the end her and here friends or sibling get away, and realize they are not in space.

I know, I know, this sounds Absolutely weird and insane! But i would really, really, like to know the name and or author of the book!
So if you recognize the description i gave, or you know a way to to find a book without the title or authors name, do tell!

thanks:)

"The Psychic Zone 5: Alien Circus" by Matthew Stone
http://www.amazon.ca/Psychic-Zone-Alien-Circus/dp/0340698373/ref=sr_1_1?ie=UTF8&s=books&qid=1233467009&sr=1-1
[young gymnasts are forced to perform for the aliens; watching the kids keeps the aliens young]

Teacher's Pet Training Academy - Cat Luring and Clicker Training


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