Disclosure: This post contains affiliate links. I may earn a small commission at no extra cost to you. Learn more
Santa’s sleigh crashed and he needs shelter! Can your kids build a marshmallow igloo to save the day? Grab free worksheet and let the engineering fun begin.
Oh no! Santa’s sleigh malfunctioned and crashed somewhere in the frozen tundra, miles away from the North Pole. He needs shelter for the night while the elves come to rescue him. Can your kids engineer an igloo strong enough to protect Santa from the cold?
This igloo STEM challenge turns marshmallows and toothpicks into a real engineering project. Kids get to build a dome structure – just like real igloos – and discover why this shape has kept Arctic peoples warm for thousands of years.
Why Igloos Are an Engineering Marvel
Here’s what makes this challenge so cool (pun intended): igloos are dome-shaped, one of the strongest structures in engineering. The curved walls distribute weight evenly, making the structure more stable than a regular box.
When your kids build their marshmallow toothpick igloo, they’re actually learning about:
- Dome structures and why curved shapes are stronger than flat ones
- Load-bearing walls that support weight from all directions
- Stability and what makes buildings stand up (or fall down!)
- Problem-solving when things don’t go as planned
Don’t worry if their first attempt collapses. That’s engineering! Real engineers test, fail, and try again all the time.
Build an Igloo Challenge
Materials:
- Regular marshmallows (mini marshmallows work too — see age variations below)
- Toothpicks
- Timer
- Small figurine for testing (LEGO Santa works great!)
- Free Build an Igloo Challenge worksheets
Instructions:
1. Give your kids a bag of regular marshmallows and toothpicks. They cannot use any other materials to build the igloo.
Set a time limit for your kids to design and build their igloo. I recommend around 5-10 minutes for planning and 20-30 minutes for construction.
Hand your child the worksheet and let them sketch out their igloo idea. Ask a few guiding questions: How will you make it round? Where should the door go? This planning step is actually a big deal in real engineering – even if their drawing looks like a blob, they’re thinking ahead.
2. Start with a circle of marshmallows connected by toothpicks. This is the foundation that holds everything up. If it’s wobbly now, it’s only going to get wobblier – so encourage them to make it sturdy before moving on.
3. Here’s where things get interesting. Each new row needs to lean slightly inward to create that dome shape. This part takes some trial and error. When it collapses (and it probably will at least once), just say “that’s what engineers do!” and hand them more marshmallows.
4. When time’s up – or when they declare it done – gently push on the walls. Does it hold? Pop your mini figurine inside. If he fits and the roof doesn’t cave in, you’ve got a successful shelter! Time to celebrate.
As LEGO fans, we do have a LEGO Santa in our collection. So, of course, we have to place the Santa in the igloo to see if he can actually sleep there for the night! It looks like the marshmallow igloo would make for a wonderful shelter in the North Pole.
Tips for Success
- Slightly stale marshmallows actually work better – they’re firmer and hold their shape
- If the dome keeps collapsing, try building smaller sections and connecting them
Grab the Free Worksheets
The printable worksheets help kids plan their design before building and reflect on what worked (and what didn’t) afterward. This reflection piece is where the real learning happens!
You can grab the free Build an Igloo Challenge worksheets by filling out the form below.
Now that we are sure Santa is nice and safe, our job is done here. Hopefully he’ll remember this beautiful igloo and add your little engineers to the nice list!
Merry Christmas!
More Christmas STEM fun:
can we use mini marshmallows or are normal-size ones better?
The normal-size ones will just create a giant igloo – why not!