Chad and the Marathon is the 17th episode of Season 3, the 107th episode overall of Clarence.
When Chad realizes his lazy habits might be rubbing off on Clarence, he decides to participate in the Aberdale Marathon.
The episode starts off where Chad gives Clarence a piggy back ride to school. Then he put a toy dinosaur in Clarence's lunch bag. In class, Clarence found the dinosaur toy and like it. Ms. Baker tells her class to do reports about people they look up to. Chelsea asked if she can do a report about her aunt, Baker said she can. Jeff then ask he can do one about his uncle, Baker said he can but not in a happy way. Clarence decide to do a report about Chad.