By Science Mom
My five-year old son, Alexander, has already developed a strong interest in math and science. At his request, we recently enrolled him in an after-school astronomy class, where he draws stars and shoots the galaxy breeze with the other pupils. He has settled on Saturn as his favorite and most interesting planet; he loves the rings.
As part of a plan to nurture Alex’ interest in science, I decided that each week, he and I should try some form of scientific experiment. With that in mind, Talking Science helped me out by giving me access to Mick O’Hare’s great book, How to Fossilize Your Hamster And Other Amazing Experiments for the Armchair Scientist.
Alex particularly wanted to try one experiment from the book; Bouncing Rice -- where a grain of cooked rice bounces up and down in glass of fizzy drink. Sounds easy enough, right? Alex and I thought so. Hmmm. As it turned out, instant armchair scientists we weren’t.
According to O’Hare, the armchair scientist need only drop a grain of cooked rice into a glass of soda and wait for the rice, buoyed by the bubbles of carbon dioxide in the soda, to start rising and falling. Where did Alex and I go wrong?
We started by filling two shot glasses with selzer water. We put a single grain of rice in one, and three grains in the other, watched them sink to the bottom, and waited. Nothing. The grains twitched a little, but showed no sign of rising up anywhere. Alex had his face inches from the shot glasses, willing the rice to move. At one stage he also went and got his magnifying glass, to make sure he wasn’t missing anything. Still no luck.
We discussed that maybe the rice was the problem, because it was boil-in-the-bag. But it was all we had, so we decided to change beverages, and we filled another shot glass with Diet Coke, dropped in a grain of rice and waited. Nothing. Although we could barely even make out the rice through the murky gloom of Diet Coke brown, it definitely was not moving.
With Alex’s attention starting wander, we decided to further diversify both the range of glasses and the beverages we were using for the experiment. Half an hour after we started, we had ten vessels full of fizzy drinks, including two shot glasses full of selzer water, one shot glass of diet coke, one large beer glass and one small mug of selzer water, one champagne flute full of ginger ale, another champagne flute full of tonic water, one Bob-The-Builder tumbler full of ginger ale, and an Irish coffee glass full on tonic water. And at the bottom of each? Stubborn grains of rice, all lying very, very still
SO THAT’S WHY THEY CALL IT “SPRITE”
Then Alex spied the remains of a bottle of Sprite in the refrigerator and suggested we use that. I was worried that it might be flat, but I emptied it into a regular-sized tumbler. Then Alex added the grain of rice, and we watched and waited.
But not for long. The rice went beserk!! It bounced up and down like a jumping bean. Alex squealed with delight, and declared the experiment ‘cool.’ Then, in order to reassure that it was the Sprite, and not the size of the glass that triggered the success, we repeated the experiment by pouring Sprite into a shot glass, and then adding a grain of rice. The rice nearly jumped out of its skin it was moving so fast.
Alex and I are going to try one experiment per week. Next week, we’re tossing up between testing the dynamics of our freezer door, or trying to create ‘clouds’ of smoke inside a plastic bottle. We’ll keep you posted.
Editor's note: This is a re-post from March 1st, 2009 because the original seems to have vanished.