I Spent My Summer Vacation Kidnapped Into Space (Vintage Paperback) by Martyn Godfrey

What a way to start the summer!

On the last day of sixth grade, Reeann and her best friend Jared (who just happens to be the cutest boy in school) are innocently hunting rocks among the asteroids. Suddenly they meet a very shaggy pair of Torkan aliens. One of the Torkans aims a freeze pistol at them. "Be silent or you die!" he says.

The next thing Reeann knows, her friendship with Jared is put to a severe test as they are kidnapped to the forbidden planet of Freetal-to be put in an arena to fight giant Andovian slime worms for the entertainment of the aliens!

And the summer is just beginning. Reeann can't believe what is happening. Is this any way to spend a summer vacation?