They make their first appearances during the song sequence, After Today. They appear suddenly and he plans to go swimming. It implies going to the pool with each other. But when Max Goof appears and interrupts them, they go away, this means that Lisa missed a broke. At the end of the song, They are about to kiss just when the school bell rings. As Max falls from bleachers, Lisa, Chad, and other students laugh at him.
Later, during the school assembly, the student body president, Stacey, is giving a speech to the students. The students are shown to be excited, but they grow silent as Principal Mazur comes on stage to give his speech. Principal Mazur begins giving a speech on ways to spend summer vacation, most of which include school work. The boring speech causes most of the school to fall asleep. Chad, sitting behind without Lisa took the opportunity to ask Roxanne to go with him to the party. To the end of the song Stand Out, Chad is seen looking up in amazement as Max disguised in Powerline flies to Roxanne.
Chad's not seen in the crowd cheering Max just before the reprise of Stand Out. The Powerline's show certainly did not rained Chad, and unlike other boys who did not like Max but complimented, it has not changed his mind about Max. He may be jealous of Max.
They're not seen until the end of the film, he is seen at Stacy's party next to each other behind Stacy and Roxanne reassures her, and indeed Max and Goofy soon appear on stage.
As Lisa flirts with Max instead of Chad, perhaps it meant that before school finished, She and Chad broke up and Chad sits behind Roxanne and asks her to leave with him to make Lisa jealous. It is assumed at Stacey's party they are reunited.