Students investigate Archimedes' Principle and show how it relates to density. In this Archimedes' Principle lesson plan, students experiment with a beaker of water, a Styrofoam "boat" and a weight. They predict what will happen when the weight is taken out of the beaker of water and placed on the boat. They collect the amount of water displaced by the weight on the boat and compare it to the mass of the weight outside of the water.