Smoke Rings

1 large-mouthed, clear glass quart jar
red food coloring
small baby food jar
6-inch square of foil
rubber band
pencil
1 ice cube
1) Place the ice cube in the baby food jar. Fill the jar with cold water.
2) Fill quart jar within an inch of the top with hot water.
3) Remove ice from baby food jar. Stir in 6-7 drops of food coloring.
4) Cover the mouth of the baby food jar with foil; use the rubber band to secure the foil.
5) Use the point of the pencil to poke a small hole in the foil.
6) Quickly turn the baby food jar up-side down and hold it so that the hole is just under the hot water.
7) Slowly and gently tap the bottom of the baby food jar with pencil eraser or finger. Explanation: The taps make the cold water flow out in smoke-like rings. Because warm water is less dense than cold water, the rings sink to the bottom.