Make a Salt Volcano (Lava Lite)

This activity about density provides instructions for making a miniature "lava lite" with just salt, oil, water, and food coloring. This crowd-pleasing experiment is a hands-on and colorful way to explore how substances less dense than water (like oil) will float in water, while substances more dense than water (like salt) will sink. The activity can be a demonstration, with the instructor creating one lava lite, or it can be a hands-on activity, with each learner making her or his own lite.