Lesson Summary The focus of this lesson is size and its affect on buoyancy. The students create different sized aluminum boats that have the same designs. Students experience the upward force of the water, and observe how the boat moves down into the water as marbles are added.  Students use their sense of touch to explore the buoyant force of water on their boats, and relate this to the size of boat. Students predict and test how many marbles each boat will hold. Teacher Background The amount of under water space (volume) the object occupies is directly related to buoyancy. Large objects displace more liquid than small objects. For example, large boats displace a large amount of liquid, making the buoyant force on them greater than the buoyant force on small boats. It is important for students to engage in their own struggle to make sense of what they observe, rather than using the scientific vocabulary to explain their ideas. Set-up/Management Tips Different size of aluminum foil pieces need to be cut ahead of time. (see manual for specific sizes) If water has been saved in containers, it can be reused for this investigation. Set up multiple testing stations. Literacy Support Scientific Vocabulary The following words are key vocabulary words that will be introduced in this lesson and reinforced throughout the unit: Displace - Displacement