Can a balloon blow up inside of a water bottle?

Second Grade Science is really fun. My two teachers make it really interesting. One day they asked if you could put a balloon in a water bottle and blow the balloon up. They wanted us to do a crazy experiment that I thought would work, but it turns out--I was wrong!

They started the lesson by giving two of us a balloon and asked, "What is in the inside of the balloon?" I knew what the answer was--There was gas in the balloon. Then they asked, "Can you have a balloon fastened to the top of a water bottle and blow up the balloon inside the bottle?" My hypothesis was--yes, you could blow it up, because I had air to blow into the balloon. Our teachers sent us back to our seats to explore our experiment. I went back to my seat and got started immediately.

I picked up the water bottle and blew as hard as I could. But, guess what, NOTHING happened! The balloon did not inflate inside of the water bottle. I was asking myself in my head--"What?" "Why won't it inflate?" I looked around but all the other kids didn't have success either. Nobody's balloon was blowing up inside their water bottle. It hits me like a ton of bricks. It is because there is already gas in the water bottle. The balloon can't hold air because there is the gas inside of it.

Some kids decided to squeeze the bottle and the balloon popped right out of the top of the water bottle into the air! It inflated backward! As they squeezed it, the air in the water bottle went backward and inflated the balloon. Amazing!

As soon as we finished testing our hypothesis, I wrote my conclusion on my lab sheet. My conclusion was--The balloon did not inflate inside the water bottle because there was already gas inside of the water bottle. For the balloon to inflate nothing else could have been taking up the space inside the balloon.

My teachers had research books out on our tables to read when we were done with our conclusions. I read about the insects of nature while the other kids were finishing their experiment.

My teachers rang the bell and called us up to the carpet for Closing Session. The teachers invited kids to share their hypothesis and their conclusions. When the kids were finished sharing their notes, now the teacher gets a little bit crazy and asks, "What would happen if I put a hole in the water bottle, children?" "Would I be able to blow up the balloon with a hole in the bottle?" I think in my head--It should be able to blow up because if there is a hole, when you blow up the balloon gas will escape from the hole, leaving more space in the bottle for the balloon to get blown up. As I raised my hand, I tried to remember what I had thought of in my head. I wanted to share my hypothesis with the class. My teachers called on me and I told the students that I thought the balloon would blow up because all of the oxygen and gas would go out of the hole and the balloon would blow up with no problem. My teacher does the experiment and what do you know, I was actually right!

This is just one of the experiments I did this year. I do tons more than just this. But, I think this one was my favorite so far in Second Grade. I think Science is awesome!

From the Science Learner,

Little Brother