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Even though it’s in the 70s here in North Texas, we are still technically in the middle of winter. So then, what better time than now to build a marshmallow igloo and talk about the STEM behind them?
This experiment demonstrates the science and engineering behind igloos by letting kids build their own igloos out of marshmallows and glue. It teaches how to build a stable structure, the science of how igloos keep people warm, and even allows little ones to build on their fine motor skills.
Time to get building!

How to make the Marshmallow Igloo STEM experiment
Supplies you will need
For this experiment, you’ll need:
- Mini marshmallows
- Paper bowl
- Glue
- Empty toilet paper roll
- Scissors
Here’s a great book about igloos that would be excellent to accompany this experiment!

Before you start
We really enjoyed having a conversation about igloos while we made it. If you have time before the experiment, look up some interesting facts about igloos to get the conversation started, or you can go to the end of this post in the “STEM behind” section to learn some cool facts!
Instructions
Here is how to do this experiment with your child:
Step 1: Cut an opening in the paper bowl for the toilet paper roll
Line up the paper bowl to the toilet paper roll to see about how big you need to cut the bowl. Leave just enough space to fit the toilet paper roll inside of it.

Step 2: Cut down the toilet paper roll
First, cut the toilet paper roll in half. You’ll only need one of them to make an igloo.
Next, cut the half roll so that it is as tall as the opening in the bowl that you cut in step 1 (see the second picture).
Add some glue to the toilet paper roll and press the bowl on top of it to connect the two pieces.




Step 3: Glue the first row of marshmallows
Now, the fun part! Add a line of glue to the bottom of the lip of the bowl, then place marshmallows side-by-side until you have finished the row of marshmallows.

Step 4: Continue adding marshmallows up the bowl and around the door
We wanted our igloo to look as close to the real thing as possible, so we decided to stagger our marshmallows so they weren’t stacked directly on top of one another.
Once you have finished working your way up the bowl and have added the last row on top, begin adding marshmallows with glue around the doorway of the igloo. Start as close to the existing marshmallows as you can and work your way toward the igloo opening.


The STEM behind the Marshmallow Igloo experiment
This experiment teaches:
- Engineering and design
- Science of igloos
- Fine motor skills
How it works
The Marshmallow Igloo STEM experiment demonstrates the science and engineering behind igloos by letting kids build their own igloo out of marshmallows and glue.
This experiment introduces small children to engineering and design by allowing them to play with the building process and figure out the best way to build a stable igloo successfully.
It’s also a great opportunity to learn some fun facts about igloos, like how the dome shape of the igloo is not just for structural integrity but also to reduce the surface area to the cold outside!
Finally, this is a great fine motor skill development. This activity can help smaller children with their hand-eye coordination and dexterity by carefully placing each marshmallow in a row on the igloo.
Engineering and design
Even though we’re only gluing mini marshmallows to a bowl, we can still learn about some basic engineering and design principles!
We can teach the kids about layering the marshmallows on top of one another versus staggering them, and which might be more durable when building an igloo. It’s best to stagger the marshmallows because it creates more stability, helps with weight distribution, and ultimately gives the igloo more structural integrity.
Science of igloos
Igloos are FASCINATING! Here are a few cool (pun intended) features about igloos to talk about in your experiment (that hopefully spark even more exploration about igloos):
- The primary building material in igloos is compressed snow, which traps a lot of air in between its ice crystals. That air acts like a barrier, significantly reducing heat transfer between the warm interior and cold exterior.
- The dome shape of the igloo is not only for structure stability but also to reduce surface area to the cold outside.
- The warmth from the occupants melts the innermost layer of snow and turns it into ice, which further contributes to insulation inside the igloo!
If your child seems very interested in igloos, you can read about them together here. You can also check out this book to read with your child
!
Fine motor skills
Carefully stacking and adding marshmallows to the igloo will help develop hand-eye coordination and dexterity. If they’re not stacked carefully, you might get some sliding marshmallows on your structure!
More experiments about building structures to try out with your child
- Build a Pratt truss bridge: Popsicle sticks and glue to hold 50+ pounds!
- Straw Structures: How much weight can straws hold when they work together?
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