by Colie Haahr, CMNH Educator
We did a mini rocket experiment for this Spooky Science video, and made a bat straw rocket. You can try both at home! For the mini bat rocket, it's important to have supervision and assistance from a grown up. This experiment uses medicine, and children should not try this without help from a grown up.
Bat Rocket Experiment:
- Alka seltzer or similar effervescent medicine
- A film canister with a tight fitting lid
- Optional: a bat to add to your rocket. We used a laminated picture in the video
Set up outside or use a tray indoors in an area that's easy to clean up
This experiment happens quickly! So make sure all eyes are on the rocket once the ingredients are inside.
Break off a piece of the alka seltzer and place it inside the film canister. Add water filling the container less than half way. Quickly replace the lid of the canister, and flip it over so that the lid is on the ground (or tray). Wait less than a minute, and the canister will launch into the air!
How does it work?
The alka seltzer mixes with water and creates bubbles. Another way to describe it is that a solid and a liquid mix together and create a gas. In the small canister there is only so much space for the water and the bubbles to fit, so the pressure from the bubbles pushes the canister up into the air! The bubbles are carbon dioxide gas, and as the gas is trying to escape and has nowhere to go, it pushes the lid off of the canister. Since the canister was placed upside down, the canister flies up into the air rather than the lid just flying off (that will happen if the canister is placed right side up!). This experiment is similar to a baking soda and vinegar experiment, and that's because some of the same ingredients are in the alka seltzer- citric acid and sodium bicarbonate.
Bat Straw Rocket Activity:
For a less messy version of bat rocket fun, try making a bat straw rocket!
- Bat template
- First, print the bat template on the cardstock, or use a permanent marker to draw a bat
- Color the bat in with markers or crayons, and cut it out
- Cut a pipette so that the larger end can be used for the rocket (the part you squeeze)
- Tape the pipette piece onto the back of the bat cut out
- Place the pipette piece onto a straw- this can be a reusable straw, paper straw, or plastic straw
- Blow into the straw with is angles slightly upward- the bat should "fly" off of the straw
How does it work?
The pipette piece is closed off at the top, so when you blow into the straw, the air has nowhere to go. The pressure from blowing into the straw makes the bat fly off the straw, and go through the air for a bit!
We first learned about this activity from Bug and Buddy, and they have a free printable bat template that can be used for this project. There are also some great pictures of the process to make the rockets, and a video. See the link in the reference section below! This activity involves pressure and forces similar to the bat rocket experiment, but it is less messy and can be tried over and over again. Have fun!