Weather - water cycle liter soda bottle cut in half. Put about an inch and a half of warm water (w blue food coloring) in the bottom. Invert the top of the bottle with the lid on and fill with ice. Watch the water condensate and watch it "rain")
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.