After drinking the water, Jake feels a little strange. Shrugging the sensation off, he runs back out of the woods to get ready for school.
As Jake walks to school, he feels another strange sensation, kind of like an upset stomach. Not worrying about it too much, Jake continues on his way.
Jake finally makes it to school, having not been bothered by the strange feeling any more. As he says hi to a couple friends and sits down at his desk, he prepares himself for a normal day. However, right before Jake's teacher starts to go into their first lesson of the day, Jake feels a strange itching feeling running over his body.
Looking down, he sees that gray hairs are sprouting out of his arms, and presumably the rest of his body. Eventually the hair gets thicker, covering his whole body from head to toe. Running his hand on his new fur, Jake is surprised to see how soft it is. Feeling changes happening in his hands, Jake looks down to see his hands turning into paws and his nails sharpening into claws. Carefully taking off his shoes, Jake sees the same thing happening to his feet.
As the teacher drones on about multiplication, Jake hears a series of cracks running up and down his body and doubles over in pain as his bones shift, as well as his organs. Now hunched over into a painful sitting position in a desk, Jake finds that he can straighten himself up, but only for short periods of time. Feeling an odd tug just over his rear end, Jake hears a ripping sound as a long bald tail shoots out of his pants.
Suddenly going deaf, Jake raises his paws to his furry head to try to locate his ears, which have rounded and migrated to the top of his head. His face then pushes out into a rodent-like muzzle, and whiskers sprout out on either side of his nose. Then the last few changes complete themselves as Jake, now a rat, shrinks down to his proper size. As Jake climbs out of his clothes that have fallen over him, he hears the bell ring for lunch. Realizing he can still communicate, Jake tries to think of a way he can get out of this mess, but not before getting some cheese.