"Professor Rotwood's Thesis" is the seventh episode of American Dragon: Jake Long.
One night, Professor Rotwood manages to take a blurred picture of Jake and Huntsgirl fighting. The next day, in class, he hands out fliers saying he is offering a $500 reward for evidence of the magical creature that was loose in New York City.
While Jake, Trixie, and Spud are at Trixie's house, they (or Trixie) accidentally break a vase. The three try to find a way to buy another one. It turns out the vase is worth $600. While trying to earn money, Jake brings up the idea of earning at least five hundred dollars. He decides to give Professor Rotwood a few pictures of himself in dragon form. After the evidence is rejected, he turns in his scales and it is still rejected.
On his way home, Jake spots Huntsgirl trying to steal the gold from a leprechaun. While the two battle, Huntsgirl knocks Jake into a building and he goes unconscious. Trixie and Spud are down below, trying to find a way to get more money. They spot the dragon, unaware that it is also Jake, lying in the alley. They decide to turn him in for money.
When they turn him in to Professor Rotwood, they are rewarded with the cash. The two decide to go to Jake's house to tell him the news. After Haley lets them into his room, they wonder where he could be. When Spud sits down, he turned on the computer and they both spot images of Jake as a dragon--Jake forgot to delete the images from his computer. There are images of him "dragoning up." They find it unbelievable, but decide to get him back from Professor Rotwood.
At his residence, he is denied a refund, so Trixie and Spud go to Jake's Grandpa's shop. After finding out magical creatures exist, Trixie and Spud get help from Grandpa and Fu Dog. Fu Dog drives a taxi, while the others ride in the back. After Professor Rotwood puts oil behind the taxi, it swerves through the driveway and they get stuck in a traffic jam. Meanwhile, Trixie and Spud give up all their money to a taxi driver to get them to where Professor Rotwood and Jake are.
As Professor Rotwood is talking to the other people, Trixie and Spud struggle to free Jake. They come up with a plan and when Professor Rotwood opens the back of the truck, he sees Jake in a dragon mask, which he takes off. After they arrest Professor Rotwood, Jake thanks Trixie and Spud for saving them.
Later, Jake is at the shop with Grandpa and Fu Dog. Fu Dog makes a mind-erase potion to make Trixie and Spud forget every magical event that ever happened. Just before Jake arrives at Trixie's house, he finds the leprechaun, who thanks him with a piece of gold. Jake goes off to buy the replacement vase before going to Trixie's house. On his way there, he dumps the potion into a plant, then joins his best friends to play a video game. Meanwhile, in jail, Professor Rotwood has grown suspicious that Jake is the dragon.