Lesson Summary Students focus on the buoyant force itself by measuring and comparing the force needed to pull three different-sized fishing bobbers completely under water. They discover that the larger the bobber, the greater the upward force of the water. Teacher Background The buoyant force is exerted on all objects in water, regardless of whether they sink or float. An object will float if the buoyant force on it is equal to or greater than the downward force of gravity. An object will sink if the upward buoyant force on it is less than the downward force of gravity. Set-up/Management Tips Teacher should do this investigation before introducing the lesson to students. 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: Continue to use vocabulary introduced in previous lessons.