Cub Scout Activity: Alka-Seltzer Rockets

Alka-Seltzer Rocket Supplies

10, 9, 8, 7, 6…  This cool Cub Scout activity has all the elements for a fun den meeting or pack meeting:  boys, rockets and explosions!

This Alka-Seltzer rocket 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 boys with 200 rocket explosions was GREAT!

While this Cub Scout activity only fulfills one Adventure requirement, it is a super fun activity for all the boys.  You could even make these rockets during your Space Derby.

Webelos/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.

How It Works:

Basically, the gas produced by the Alka-Seltzer and water builds up in the film canister until there is enough pressure to blow the lid off the canister 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.”

Supplies Needed:

    • Film Canisters – The ones where the lid fits inside the canister.  The other kind won’t work.  Because so many people use digital cameras instead of film cameras, these are getting more difficult to buy.  eBay is probably your best source if you need quite a few.  For just 3 or 4, talk to your local film developing store (Walgreens, CVS, Target, etc.) and ask if they can save some for you.
    • Alka-Seltzer tablets – Generic brands also work well.
    • Water

That’s really all you need for the project.  But to make the canister look like a real rocket, you can print and attach the body, fins and cone.

The original designs were taken from this site, but you have to resize the images.  I did that and turned them into printable jpg files for you.  You can pick the color you want or you can print the black and white version for the boys to decorate themselves.  Here is an example of the template:

Rocket template red & grey

Downloadable & Printable Templates:

If you decide to use the templates, you’ll also need:

  • Scissors
  • Tape
  • Crayons, markers or stickers for decorations

How to Build the Rocket:

  1. To decorate the canister, print off one of the templates and cut it out along the solid lines.  Fold along the dotted lines.
  2. Tape the body around the canister making sure the open part of the canister is pointing down.
  3. Roll the nose into a cone, center it on the canister and tape it down.
  4. 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 boys.

This site has illustrated instructions.  There are also directions on how to make and use a launch pad.  We opted to use our driveway for the launch site!

How to Launch:

First, make sure everyone is well away from the launch site except for the boy whose rocket is about to launch.  Turn the rocket upside down and pour water into the container.

Alka Seltzer Rocket adding water

Drop an Alka-Seltzer into the water and quickly put the lid on.  Make sure the lid snaps completely into the container.  Then RUN!  Seriously, you should move quickly away from the launch site.

Alka Seltzer Rocket ready for launchHave the boys can count down!

Alka Seltzer Rocket 1

Blast off!  This one went flying!

Alka Seltzer Rocket trail

My camera is a point and shoot, so even in sports mode, I wasn’t able to get any shots of the rocket in the air.  But you can see the trail made by the rocket.

Alka Seltzer Rocket not very far

Too much water in this launch for very much height.

A Few 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 1/2 full) for the most height.  In the picture above, the canister was about 3/4 full which didn’t leave much room for the gas.
  • When you tape the paper onto the canister, make sure the paper 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 a second time.  It will most likely be laying on top of the lid at the launch site.

Hope your den has as much FUN with this activity as we did!

Yours in Scouting,

P.S. If you would like to see a great family movie with some boys building rockets, check out my movie and book recommendation.

Thanks to for the inspiration and templates!

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14 thoughts on “Cub Scout Activity: Alka-Seltzer Rockets

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  2. Gail

    Trying this with my Bears tonight. I had to resize the templates because yours weren’t 7.6 by 10 inches like the original site listed. When I printed yours, they were too small. My practice runs went well. Thanks!

  3. Jessica

    This is great! We’re going to use it for our rocketry badge in my Curiosity Hacked Sparks group! Thank you for sharing, I was having a hard time getting this to work with test tubes. The film canisters are MUCH better!

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  5. Susan S.

    Can you re-use the film canisters again or does the gas/explosion damage them so its just a one shot deal?

    Love your site!
    Pack 128 Jacksonville, FL

    1. Rebecca

      OK. The medicine bottles worked and I blew up the pattern slightly, since they were taller. I do want to say, though that using the rocket pattern was fun, but kind of a waste of time. The boys spent much longer decorating and putting them on than I expected. At the end not one rocket had the paper still on it. They got wet and fell off quickly. The rockets worked perfectly fine without them. If you want to make it look like a rocket, I would consider only using the cone at the top and perhaps laminating them, so they don’t get too wet.

  6. Deb Carreno

    These were AMAZING. The boys had a BLAST (pun intended)! The size of the pattern was a bit off but nobody cared. I was putting water in the canisters as fast as I could and was not able to keep up with the demand from the boys. They just wanted to keep doing it again and again and again… We had only 10-12 boys tonight but we still went through a box of 28 tablets (and they were used more than once). This is something that will definitely be in my list of repeat activities!


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