Arnold organizes a campaign to save the oldest tree in the neighborhood. Mr. Simmons is accepted by Arnold and the rest of the class as their new teacher after they're tormented by a mean substitute.
Save the Tree: Arnold and the gang must stop Big Bob from chopping down the oldest tree in town. New Teacher: After the kids scare away their new, sensitive teacher, they end up with a dictator, and have to convince the former to come back.