Density Tower

In this Incredible Science experiment, you’ll see how three different liquids can stack up — and stay on different levels. It looks like magic, but it’s really just density at work. Take the experiment further by dropping different objects into your tower to see how — and where — they float.

You will need:

water (with food coloring, optional)

corn syrup

lamp oil*

cup, drinking glass, or vase

spoon or skewer, optional

small objects, such as a screw or bolt, grape, dice, bottle cap, ping-pong ball, and so on

*I had some leftover lamp oil from Chanukah, which I colored with lamp-oil coloring. It looks cool, but it’s not necessary. Clear is fine!

How to do it:

1. Fill a cup (or drinking glass or vase) about ⅓ of the way with water. Add food coloring if you like.
2. Pour an equal amount of corn syrup into the cup with the water. It will sink to the bottom because it’s denser.
3. Add the lamp oil. It will float to the top because it has the lowest density of the three liquids.
4. Take a moment to admire your density tower. You can even stir it with a spoon or skewer and watch it separate into layers again.
5. Now start experimenting with your objects. Drop in a screw or bolt, and watch it sink to the bottom.
6. Try dropping in a grape or a single die. This should float on top of the corn syrup.
7. Take the plastic cap from a bottle of soda or water, pushing it upside down into the lamp oil so it fills with oil. It should float on top of the water.
8. Finally, drop in a ping-pong ball. Is it floating on top of the oil layer?

Take it further

Look around for other small objects you can drop in and observe (think erasers, pen caps, paper clips, corks, and the like) and see what you can get to float in the various layers.