Marnie is the music teacher at Port Doover Elementary. She makes very few appearances and rarely has any speaking lines.
In "There's a New Principal in Town", she is tricked into leaving her class, by Luc, over the intercom, claiming that her scooter was being towed from the parking lot, so that she can be substituted with Coach Lessard.
In "Bald is Beautiful", Luc mixed up her music class by rubbing his bald head to a rap tune, getting the entire class to cheer for him. The next Monday, when everyone was hairier, they hated him for it and threw him out of the class.
In "A Kyle in His Shoes", she was taking on the role of a completely different character. In this episode, she was portrayed as an old lady who had nothing to do with the actual Marie. She was in need of crossing the street and Kyle helped her. However, a snail was in their way, so it took them the entire day to get across, only for the old lady to mention that she forgot her purse on the other side of the road.
In "Power Plant", she was one of the many teachers in the lounge to be horrified by the coffee machine breaking down.
In "Glitch Girl", it was revealed that she, Lunchlady Trudy, Nam Nam, and Jerry's Nanny were part of a girls rollerblading team called "The Whipper Snappers" back in the day, with the signature move "The Afghan Slam". Her stage name was "Mrs. Mindblower". Luc set them up against the current girls rollerblading team. She tried to attack "The Pink Fury", but she fought back by picking up "Toriadora" and whacking her off the road with him.
- There's a New Principal in Town
- Wizard of Wacker Maze
- Bald is Beautiful
- A Kyle in His Shoes (Different Persona)
- Power Plant
- Glitch Girl
- When she spoke in "Wizard of Wacker Maze", she had an Irish accent. When she spoke in "A Kyle in His Shoes", she had an old lady voice, though she was a different character at this time.
- In the episode "There's a New Principal in Town", it was revealed that she drove a scooter with a bumper sticker that read "My other car is a saxophone".
- In "A Kyle in His Shoes", she was portrayed as a completely different character than her usual role. She was an old lady, who took the entire day to cross the street,