Lesson Summary Students work with salt water to investigate the effect that a heavier liquid has on an object’s buoyancy.  Students are introduced to salt water as a solution. They predict observe how various amounts of salt interact with and dissolve in a drop of water.  Students discover that salt water is heavier than fresh water.  They observe and describe the changes in salt water over time. Teacher Background Students are asked to make predictions about how salt will interact with fresh water. During this investigation, students begin to question and create theories about their observations. Effective questioning on the teachers part will help facilitate this process. Set-up/Management Tips Ahead of time, pieces of wax paper need to be cut in 4 inch squares. Ahead of time, pour salt into 15 plastic cups, so that each is ¼ full. Prepare small spoons with masking tape for overnight investigation. If water has been saved in containers, it can be reused for this investigation. Set up multiple testing stations. Be sure students wash hands after using salt to prevent drying out of skin. Salt needs to be stored in a sealed container so it will not absorb water from the air.  Place a few rice grains in the salt container to prevent clumping. Literacy Support Scientific Vocabulary The following words are key vocabulary words that will be introduced in this lesson and reinforced throughout the unit: Saturated Salt Solution