Mr. Young Season 3

The morning after Halloween, the gang tries to remember what they did during their candy-fueled haze the night before

Arthur returns and makes Adam & Echo babysit Arthur's kids. Meanwhile, Derby and Ivy decide to dress up as robots so they can make friends with Arthur. ARTHUR returns to Finnegan with his new robot family and asks Adam to babysit his "grandkids." Adam agrees and tries to impress Echo with his parenting skills, but soon realizes that dealing with kids is not as easy as it looks.

The class goes to a Magic Mansion. Adam tries to get rid of everyone with a "magic box" so he and Echo can be alone, and in a string of odd events later ends up trying to saw Echo in half. Meanwhile, Principal Tater tries to get a new membership card.

Adam can't get peace and quiet so he buys his own apartment. Thing go wrong when everyone piles in for their own reason. So now, with the help of his mom, they try to get out of the lease. Meanwhile, Tater enlists that Dang help in fooling his new girlfriend Gwen that he's a billionaire living in a mansion. He ends up telling her the truth thinking that she'll like him better but she doesn't and she leaves. Adam ends up selling Tater his apartment.

Adam makes a drink that will make him more confident to ask Echo out, but it ends up wrong when he turns into a monster. And even worse is that whenever he talks or thinks about Echo being cute he turns into the monster. Now he must stay away from Echo to prevent from turning into the monster. But in the end, Echo accidentally drinks the potion and now when she thinks about Adam being cute she turns into a monster.

Adam accidentally gets Santa Claus's elves fired and must work to get them rehired, or feel their pint-sized wrath.

Time is accelerated after an experiment went wrong; Adam and Derby age.

Derby dates a girl and suddenly realizes that she is related to Mr. Pickles.

Adam is hired as a science advisor for a sci-fi movie being shot in Finnegan.

Adam tutors Ivy in exchange for tickets to a music festival.

Adam is determined to join Finnegan's secret club.

Echo gets sick on Valentine's Day, so Adam shrinks down to fight the cold.

After freeing a Sasquawk, a giant chicken monster, Adam is kidnapped by the beast who loves him.

Ivy invites Echo to a slumber party at the Young house; Adam must now stop Echo from discovering a shrine that exposes his true feelings for her.

When Echo decides she and Adam should set each other up on a double date, Adam must try to find a date who Echo won't fall for.

A student takes credit for writing Adam's love letter to Echo and Adam must prove that the student is lying before Echo falls for the wrong guy.

While taking Ivy on a tour of Great Northern University, Adam and his old professor tell Ivy about Adam's first day on campus.

In order to make a better first impression on Echo, Adam uses a time machine to travel back to his very first day as a science teacher.

In order to make a better first impression on his crush Echo, Adam uses a time machine to travel back to the past to meet her for the first time all over again. After returning to the present he realizes his plan has backfired and he has to time travel back again to repair his relationship with Echo. However, the time travel mishaps multiply and spiral out of control and soon Adam’s meddling in the past has him scrambling to keep from being permanently stuck there.Eventually by the end Adam decides to not change the past and goes back to the present. There Echo tells Adam that she likes him and they start dating. They then kiss. They decide to keep it a secret from everyone else.

Adam uses a time machine to go back in time so he can make a better first impression on Echo.

When Derby almost gives away the secret that Adam and Echo are dating, Adam plots to erase Derby's memory. However, Adam gets Preston Pickles to advertise and use Derby to volunteer the Memory-Erase machine but he uses Echo and erases her memory that she is in love with Adam!

Mr. Kidd's students like him a lot and think he's fun even though he does the same thing Adam does. Adam tries to change the Memory-Eraser to make it bring back Echo's memory, then Mr. Kid finds out but promises not to tell anyone or to get together with Echo. Slab and Ivy have to do a book report on George Orwell's 1984. They borrow Mr. Tater tape of the movie and when they see it they find out that Adam's mom and Tater used to date and they kissed. Ivy states that she never knew her father. Adam and Ivy's hair consistently falls out, which may mean that their father is Tater. Mr. Kid uses the reversed Memory-Eraser on Echo and they start dating. Shortly after he uses it on everyone and they forget that Adam ever existed. At the end Echo remembers Adam when they kiss. Then he restores everyone’s memory by kissing them, Mr. Kidd gets fired.

When Mrs. Straupersson is found dead, Ivy gets put on trial.

Cyclops Foods buys Finnegan High after it goes broke and tests new products on the students.

A TV news program comes to interview Adam about being the world's youngest high school teacher. To ensure the interview goes smoothly, Tater has dumped Echo, Derby, and Slab in a fake version of Finnegan High.

A Hollywood writer comes to Finnegan with the intention of making a TV show about Adam. But he is distracted by Echo, Derby, and Ivy, who all think they have better ideas for TV shows, starring themselves.

Dang is called back to Vietnam to take over for Master Ki as guardian of his village. The gang heads to Vietnam to try and convince Dang to come back to Finnegan for graduation. While there, Adam discovers an ancient scroll that points to the mythical fountain of youth, which if found, could make Master Ki young again, releasing Dang from his duties. But to find the fountain, Adam must go up against Echo who is trying to preserve the leaf monkey habitat.

While Adam and Derby explore a hidden, underground temple in search of the fountain of youth, Tater helps Echo learn about monkey behavior, and Ivy helps Slab prepare for his first ever cover model photo shoot. All roads lead to a confrontation with a local fancy hat factory owner, who has been keeping a secret from the villagers for generations. In the end, Adam gets the gang back to Finnegan, just in time for graduation.