Learners design, build, and test models of "dragon boats" made from up to three milk cartons. They observe how well the boats can be pulled through water in a homemade testing tank, and explore how changes in the design affect the boat's motion through water. A series of questions are included to help students explain the features of their designs. The lesson has background information about the history of dragon boats, and vocabulary of different parts of a boat. Extensions include calculation of the average velocity of the boat, marking the waterline of loaded and unloaded boats, and seeing the effect of saltwater on floating.