Inside out Playdough Earth - Part of hands on homeschool Earth Science unit. Also love the taking a core sample idea! This could be used in a few different grades but could be good for a grade Earth Layer activity.
Salt Volcano: Pour several inches of water into a jar. Add about of vegetable oil. Drop in food coloring and observe what happens. Shake salt on top of the oil/water/food coloring mixture. Pour or sprinkle more salt, as desired.