Lesson Summary In this lesson, students apply the results of Lesson 6, as they test designs in an effort to increase buoyancy. Students create their own boat designs and predict the amount of cargo (marbles) it will hold. They compare the number of marbles each design will hold to determine the most efficient clay boat design.  Teacher Background The buoyant force on an object depends on the amount of space the object occupies under water. When the amount of space under water is increased, the buoyant force is increased. In this lesson, the weight of the clay has not been changed, only the shape has been modified.  Predictions are very valuable in this investigation because the students’ predictions become more accurate throughout the investigation. A class discussion is very important regarding the question ‘what are you learning from your predictions?’.  Guide the students to look at their past predictions and use that information to make more reasonable predictions. Set-up/Management Tips If water has been saved in containers, it can be reused for this investigation. Set up multiple testing stations. Be sure clay is patted dry before returning to bags. Literacy Support Scientific Vocabulary The following words are key vocabulary words that will be introduced in this lesson and reinforced throughout the unit: Continue to use vocabulary introduced in previous lessons.