Buoyancy I
Object: How much does that bag of water weigh?
Materials: Small spring scale
Plastic bag or small zip lock and a string to attach to scale.
Fill bag with water being careful to rid bag of all air. Attach string and weigh bag of water in air. Before immersing bag in water, ask how much will it weighs in water? More, less or the same? How would the results be different if the bag was filled with dirt or sand? How can you relate this to catching a fish and pulling him out of the water? Why do you feel so much lighter when you jump into the water?
Lesson plan by Ray Manning, First Baptist Church School