Pleskit and Tim face off against the class pets in this tenth book in the hilarious, fast-paced, and accessible sci-fi series Sixth-Grade Alien from the bestselling author of Aliens Ate My Homework, Bruce Coville. When the hamsters in Ms. Weintraub's room start acting strangely, everyone thinks the problem must be the alien vitamins that Pleskit has been feeding them. But even after Pleskit stops the vitamin treatments, the hamsters continue to grow bigger and stronger and crankier. Clearly, something else is at work. To find out what, Tim and Pleskit must solve a mystery, track down an enemy, and defend themselves against a trio of the most dangerous hamsters the world has ever seen!