My students always get excited when they know that we are doing a science experiment. “It’s like magic, but better and real.” Today we talked about how a rocket ship blasts off into space and then guessed how we thought it was able to do this. We then created our own model that works in a similar, but very basic way compared to a rocket, but perfect for kindergarten. I always enjoy preparing science for kids because it is hands-on and kids love it!
First I blew up a balloon and asked everyone what would happen if I let go of it. I then let it go. They loved watching it zip around he classroom and then fall to the ground. We used this idea of movement for our experiment. To start, I had a volunteer hold one end of a piece of string. I then threaded a straw through the string (smoothie straws work best). I had another student hold the other end of the string and pull fairly tightly. If the string is not tight, the balloon will not go as far. I then blew up a balloon, but did not tie it, and taped it to the straw. The balloon was now filled with gas (air).
I had children guess what they thought was going to happen when I let go of the end of the balloon. After a few guesses, I then let it fly! It goes several meters depending on how full you fill the balloon. When you let the end go, the escaping air causes a force on the balloon. All the air is forced through the small hole on the balloon which causes the balloon itself to react and zoom in the other direction. Much like a rocket in blast off.
We then tried it again, but blew up the balloon more. The problem is that if the balloon is bigger, it sometimes spins and does not go as far. This leads to great discussion as to why and how we could fit this problem. We then tried attaching a small weight (a penny) to the bottom to keep the balloon from spinning. Children were also really curious what would happen if you attached 2 balloons and what about 3? What would happen if you used the huge balloon? What would happen if you held the string up so that the balloon traveled down as it moved across the string? The things that students wonder, end up being the best part of the experiment!