The activities in this unit provide experiences upon which children can build a more complete understanding of the phenomenon of buoyancy. Lesson 1 begins with a pre-unit assessment of students' ideas and questions about floating and sinking. In Lessons 2 through 5, they begin to test their ideas, focusing first on weight and size. Students make predictions and then test them with experiments. They record observations, discuss their ideas with classmates, measure the weight of a variety of objects, and begin a class graph of their observations.
Students make clay boats and explore how weight can be distributed to make a sinker into a floater.
They then load them with marbles to see how much cargo different-sized boats will keep afloat. These activities give students information about the relationship between the variables of size, weight, and design. In Lessons 9 through 12, students focus on the behavior of objects when they are submerged in water. First, they use the spring scale to measure the buoyant force on different-sized fishing bobbers. Then they measure the change in water level caused by objects submerged in a graduated tube.