Need a fun STEM activity for kids? Making these Alka Seltzer rockets fits the bill! This is one of my favorite science experiments! Read on to find out all about them including how they work, how to make them, and how to decorate them as well as some helpful tips.
When I first wrote this post back in 2013, I only talked about film canister rockets. As I'm updating this post in 2021, I decided to experiment with some alternative types of containers.
I tried three options–large 1.77 oz. mini M&M container, small 1.08 oz. mini M&M container, and the small, party favor-sized Play-Doh containers. The only one that worked was the small M&M container, and it didn't go very high–maybe 3 or 4 feet.
Frankly, I would order the film canisters. They go 15 or 20 feet into the air! Much more impressive than 3 or 4 feet. 🙂
There are several options for film canisters on Amazon. Read the recent reviews to find the ones that worked well when used for this purpose.
How Alka Seltzer Rockets Work
The Alka Seltzer antacid tablets are made of aspirin, sodium bicarbonate (which is baking soda), and citric acid. When they are dropped into water, a chemical reaction takes place, and bubbles of carbon dioxide gas are released.
The gas builds up until there is enough pressure to blow the film canister lid off and propel it into the air. It's Isaac Newton's third law of motion in action: “For every action there is an opposite and equal reaction.”
Click the image below to watch my YouTube video with lots of launches!
- Film Canisters – The ones where the lid fits inside the canister. The other kind won't work. See the image below.
- Alka Seltzer tablets – Generic brands also work. See the note below.
- Safety goggles or safety glasses
Note: Because the antacid tables contain aspirin, make sure the kids know not to put them in their mouths.
That's really all you need for the project. But to make the canister look like a real rocket, you can decorate it.
If you decide to decorate the rockets, you'll need:
How to Decorate the Alka Seltzer Rockets
You can color or draw on a piece of printer paper. Turn the canister upside down and tape the paper around it. Make sure that the lid of the canister is sticking out of the end of the paper so that you can easily remove the lid.
Another decorating option is to print this template and cut out and attach the rocket body, fins, and nose cone. You can download the templates by entering your email address below.
You can pick the color you want or just print the black and white version for the kids to decorate themselves.
How to Use the Film Canister Rocket Templates
- Print off one of the templates and cut it out along the solid lines. Fold along the dotted lines.
- Tape the body around the canister making sure the open part of the canister is pointing down.
- Roll the nose into a cone, center it on the canister and tape it down.
- Fold the fins so that they form a circle and tape them together. Slide the fins onto the bottom of the canister (open end).
If you are “spatially challenged” like I can be, practice folding the fins and wrapping the body around the canister. Once you get the hang of it, it's easy, but you'll need to know how to do it so that you can show the kids. The video below shows you how to put them together.
How to Launch Your Alka Seltzer Rockets
You need a relatively flat surface as your launch site, so we used a flat part of our driveway.
First, make sure everyone is well away from the launch site except for the person whose rocket is about to launch. Have that person put on the safety goggles.
Turn the rocket upside down and pour water into the container. The amount of water you use will determine the launch height, so only fill the container about 1/4 to 1/3 full.
You don't need a full tablet of Alka Seltzer–use 1/2 of one. Drop the tablet into the water and quickly put the lid on. Make sure the lid snaps completely into the container.
Then move quickly away from the launch site.
You'll be surprised at how high these can go when you don't use too much water.
Antacid Tablet Rocket Tips
- Tape the fins onto the canister well or they'll fly off during the launch.
- Use only a little bit of water (1/4 to 1/3 full) for the most height. If your rocket isn't going very high, try again with less water.
- When you tape paper onto the canister, make sure it doesn't go over the edge of the container. Leave a little room so that the lid will snap on easily.
- You can use the Alka-Seltzer piece a second time. It will most likely be laying on top of the lid at the launch site.
Making these rockets can be done at a den or pack meeting. The activity was such a hit at a Bear den meeting that I decided to do it with all the Cub Scout ranks during our Cub Scout Day Camp. 200 Scouts with 200 rocket explosions was so much fun!
While this Cub Scout activity only fulfills one Adventure requirement, it is super fun for all the Scouts. You could even make these rockets during your Space Derby.
Webelos and AOL Elective Adventure – Adventures in Science 3d: With adult supervision, build and launch a model rocket. Use the rocket to design a fair test to answer a question about force or motion.
Have your kids made Alka Seltzer film canister rockets? What did you do differently that worked well?
Yours in Scouting,
- Turn the rocket upside down and pour water into the container. The amount of water you use will determine the launch height, so only fill the container about 1/4 to 1/3 full.
- Drop 1/2 of an Alka Seltzer tablet into the water and quickly put the lid on. Make sure the lid snaps completely into the container.
- Set the rocket on a flat surface such as a sidewalk or driveway, and step quickly away from it.
- Wait a few seconds, and watch it go flying into the air!
P.S. If you would like to see a great family movie with some Scouts building rockets, check out my movie and book recommendation.