For their coral reef projects, the class each worked with partners. Wanda hates partnership, and instead of working with hers, Dorothy Ann, she does her own project. Ms. Frizzle tells the class about her great(x8)-grandfather, Redbeard the Pirate, leaving treasure in a coral reef, and Wanda, a wannabe pirate, wants to look for it. Ms. Frizzle tells them to go two-by-two with their partners, which Wanda teams up with Dorothy Ann, Keesha teams up with Ralphie, Tim teams up with Carlos, and Arnold teams up with Phoebe. They learn about mutualistic, symbiotic relationships in coral reefs. They are forced to work together when they see that one part of the reef has been bleached out by none other than the treasure chest. They then go back to school, and open it up, which has a portrait of Redbeard and a model of his ship that can change shape much like the bus.