Girl Scout Activities: Marimo Terrarium

As a Girl Scout troop leader, I am always busy looking for new ideas for our troop and to keep my girls entertained.  This is something you can do with a variety of ages, and it is part activity and also educational.  You can adjust the activity many different ways depending on your troop.

This is not the cheapest “craft” type of idea, but we already had some materials and you can make this into an entire meeting.  What is a Marimo?  A small algae ball that is easy to keep in a small terrarium.

Supplies needed:

Marimo moss balls
Glass jars
Rocks, glass beads, shells, “sea glass”, aquarium gravel, etc.
Ribbon or twine

The first thing I did was order the Marimos from Amazon.  There are different sizes, but the most economical way to go was to order a multi-pack of the small ones from Amazon.com.  Our Marimos were tiny, and cost $8.95 for a pack of 6 (Amazon Prime).  A single large Marimo can cost $10, so the small ones were much more cost effective.  If you order from Amazon, read the product descriptions carefully so you know exactly what size and quantity you are getting (some were even mixed sizes).

As you can see, the Marimos are definitely are small, but the girls thought they were cute!

I purchased the jars at Walmart.  They were not my ideal choice, but I wanted something with a lid and it had to be inexpensive.  These mason jars ran about $0.60 each, and I told the girls they could always switch out the jar with a different one if they wanted when they got home.  There are some gorgeous jars with corks, but those are generally at least a couple dollars each.

The key was to also find jars without a lot of markings designs, like measurements, logos, or other designs that would distort the view of the contents.

The first thing I had the girls do was start filling a jar with whatever they wanted.  I didn’t have an unlimited supply of colors when it came to the glass rocks, so I asked them to be aware of using up all of one color and making sure they were sharing with their fellow Girl Scouts.  (Being that it was Chinese New Year, we had just finished trying to eat rice with chopsticks!)

I also had regular rocks to choose from – all of which I purchased at Dollar Tree – but you can find at craft stores and online.

Next, we added a Marimo ball.

Then the girls filled their jars with water.  Ideally, you want water that has sat out for about 24 hours, so that it naturally dechlorinates.  You could prepare the water at home in a jug ahead of time.

Lastly, the girls secured their lids, and if they chose to, they tied on a ribbon.  Some of the girls also wrote on the lids, but I would have liked to be more prepared with different colors of Sharpies (as regular markers will wipe off).

As part of the experience, I wanted the kids to learn about their Marimo Moss Balls. I talked about how these are actually algae balls that grow in lakes, and how the idea of keeping Marimo balls at home originated in Japan.  I had each girl create a little care sheet so that they knew how to spell Marimo, and they wrote down that they should change the water every couple weeks and to keep the moss ball in low/medium light.  (Ideally, the water should be dechlorinated, which I explained to parents).

You can easily add other learning lessons to this activity, discussing things like photosynthesis, how plants breathe, lake ecosystems, aquarium ecosystems, and more.

This is one of our huge Marimo moss balls we have at home.  The kids love making little terrariums for friends and family as gifts.  As a troop leader, you can save the extras if your family wants to make extras with the leftover supplies.

I had fun seeing how the girls decorated their little terrariums, and they seemed intrigued at the idea of the Marimos.  While we haven’t made this part of a patch or badge unit yet, we may end up incorporating it into a spring “plants” themed patch.

Cost breakdown:
Marimo moss ball: $1.49 each
Jars: $0.61 each
Rocks and gems were $1 per bag and I used ribbons I had around the house.  Check places like Dollar Tree and Christmas Tree Shops!