Jumping Raisins

It is no secret that we enjoy the occasional science experiment at the house. So, I posed the question, “How do you make raisins jump?”

 The kids shrugged their shoulders. They seemed relatively uninterested. “Okay. I’ll figure it out myself.” I pulled out a bag of raisins making sure to crinkle the bright red bag as loud as I possibly could. The kids looked up, but didn't bite.

I opened the refrigerator  door. A bottle of Ginerale and a bottle of 7-up in my hand, I walked to the table. Thumping them down nice and loud, the kids looked up again. “What’s that?” Xander asked.

“It’s soda.” I turned to walk away to get two glasses.

“Why do you need it?” he asked again.

In my mind, I did a fist pump. I had him hooked and if he was caught, Eva would happily join in.

“It’s jumping juice for the raisins,” I said over my shoulder. I pulled two glasses out of the cupboard.

“I want to do it too!” Eva called. She climbed into the chair next to Xander as I set a glass in front of each of them.

“Okay. So, what is the first step?” I asked them. They both stared at me. “Let’s see. We have a bag of raisins, two bottles of soda, and two glasses. The only things we can’t change are the glasses so let’s start with those.”

They pulled the tall glasses in front of them. “What could we do next?”

“We could put the soda in?” Xander questioned.

I slid a soda bottle to each one. “Open them up and fill them to about here,” I said while pointing on each glass to about the ¾ full area. As they struggled to open the bottles, I opened the raisins and began to ration some out. Once done, I helped open the bottles and helped them poor them into the glasses.

The liquid fizzed appreciatively as it hit the walls of the glass and stirred itself around. The kids ahhhed and ooohhed. They also jumped back as the liquid rose faster than they had anticipated. Even I worried that it would cascade over the side. With luck and less than a centimeter, it petered out and began to lower.

“Now what?” I asked again.

“Can we put the raisins in?” Eva asked, largely having ignored my question although her response was appropriate.

“Let’s do it!” I watched as Eva gently placed one and then another in. Xander, on the other side of her, picked them all up and dropped them in at once. Another wave of fizzy bubbles threatened to pour over the side.

We sat and watched. Nothing happened. I glanced back down at the book that gave the instructions to make sure I hadn’t missed anything. Suddenly, Xander yelled, “Look!” A raisin had jumped! I looked at Eva’s glass. Two raisins were rapidly ascending, bring up with them her excitement level.

Over and over, the raisins would jump to the surface only to fall back down. We watched them for 10 minutes before I reminded them it was meant to be an educational activity. “What makes them jump up and down?” I asked.

Xander was first to give an answer. “I think the bubbles push them to the top and then the bubbles get out, but the raisins are too heavy so they fall back down.” Wow! In layman’s terms, he was absolutely correct. The carbonated bubbles would start to float up and end up stuck on a raisin. As more and more bubbles surrounded the raisin, they would lift it rapidly to the surface. Once breaking the surface of the liquid, the bubbles would pop, the carbonation released and the raisin would again fall down until it was surrounded by enough bubble to lift it.

They watched the jumping raisins for another 15 minutes. Bored with the dramatically slowed rate, they tried stirring it, adding extra soda, adding more raisins, etc. Each new experiment met with limited success, but success none the less.

The kids recorded their observations. Xander drew a picture and wrote an explanation. Eva drew a bunch of lines and squiggles that were meant to be a picture and explanation of the experiment. While they worked on that, I dumped the sodas, recycled the bottles, put away the raisins, and smiled knowing I had succeeded as well.