Floating Rice Bottle

Here's What You'll Need

Two identical plastic soda bottles with lids
Dry, uncooked rice (You will need enough to fill both bottles. Regular rice works better than the instant type.)
Two chopsticks
A tray, bowl, or dish

Let's Try It

Fill two plastic bottles up with rice. Stop when the rice is about an inch from the top.
Put the lid on one of the bottles and shake it to fluff up the rice. It should appear nearly full.
Now, we want to put some extra rice into the second bottle. To make room for the extra rice, tap the bottom of the bottle on the table. As you tap, the rice will pack down in the bottle and make room for more. Add some more rice and continue to tap. You may even want to use one of the chopsticks to make a few jabs into the rice to pack it down even better. The important thing is to make both bottles look like they are full and have the same amount of rice in them.
Invite a friend to join you and give him/her the bottle with the packed down rice. Ask him/her to push the chopstick down to the bottom of the bottle. You do the same thing with your bottle of fluffed rice and the chopstick.
Gently lift your chopstick. It should “stick” to the rice well enough to lift the bottle. Your friend’s bottle will not rise.
Offer to exchange chopsticks and repeat the demonstration. Once again, it will work just fine with your bottle of fluffed rice, while your friend’s bottle will remain on the table.

How Does It Work

When you insert the chopstick into the bottle of packed rice, it takes up additional space inside of the bottle. Because rice is not fluid and has great difficulty moving up the neck of the bottle to compensate for the space that the chopstick takes up, the packed rice has very little room to move so it tends to press against the sides of the bottle. The chopstick gets wedged between the rice and the sides of the bottle. Friction helps to hold the chopstick in the bottle as the bottle is lifted into the air.

Science Fair Connection

Creating the illusion of floating rice is pretty cool, but it isn’t a science fair project. You can create a science fair project by identifying a variable, or something that changes, in this experiment. Let’s take a look at some of the variable options that might work:

Try different sizes of chopsticks. Do different sizes hold the bottles of rice up differently?
Try different amounts of rice packed into the bottle. What is the least amount of rice that you can use to still make the bottle “float?” Is there a maximum amount of rice that you can use?
Try different types of rice. Does one type require less packing than others in order to create the necessary friction of holding the popsicle stick in?

Those are just a few ideas, but you aren’t limited to them! Try coming up with different ideas of variables and give them a try. Remember, you can only change one thing at a time.