Marshmallow Igloo Engineering Challenge

There is just something I love about Winter STEM projects – and I must say marshmallows are a great low cost – readily available material that kids love working with!  So if you’re looking for a fun and engaging winter STEM idea that combines creativity, engineering, and a bit of history you found it! We are going to challenge the kids to engineer their very own igloo using marshmallows. It’s a hands-on way to learn about the architectural ingenuity of igloos, while testing engineering and problem-solving skills.

Marshmallow Engineering Challenge: Let’s Build an Igloo

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This challenge can be adapted for different levels, offering a beginner version with marshmallows and toothpicks and a more advanced challenge that encourages kids to construct a stable igloo arch without any supporting materials. 

What Is an Igloo?

An igloo, or snow house, is a type of home or shelter from the weather traditionally built by the Inuit people in the Arctic. These dome-shaped structures were crafted from blocks of hard-packed snow and were designed to provide temporary shelter during hunting trips. Igloos are known for their incredible insulation properties—despite being made of ice and snow, they can keep the inside warm and comfortable, often reaching temperatures above freezing even in harsh Arctic conditions.  The domed structure of an igloo is designed to use gravity to hold the blocks in place against each other.  

Igloos are more than just cool (no pun intended) structures—they’re an engineering marvel. The shape of an igloo, especially its dome, distributes the weight of snow evenly, preventing it from collapsing. The igloo’s walls trap warm air inside, while the blocks of ice serve as insulation.

The Marshmallow Igloo STEM Challenge

In these marshmallow engineering challenges, kids will use marshmallows and either toothpicks or their own ingenuity to create an igloo. They will learn how to build the structures and have a chance to experiment with  stability, weight distribution, and the geometry involved in creating a dome. This amazing hands-on challenge offers a great opportunity for teamwork, creativity, and learning through trial and error (lots of trial and error!).

There are two different ways you can go about this challenge. 

The Starter Igloo Design: Use marshmallows and toothpicks to build a basic igloo structure. This one is great for your younger kids.

The Advanced Igloo Design: Build an igloo without toothpicks, focusing on creating a stable dome using just the marshmallows, requiring kids to figure out how to form a stable arch. This is a more challenging project for your advanced kids.

How to Build a Simple Marshmallow Igloo

STEP 1

You will need: Toothpicks and Marshmallows. We used the large marshmallows but you can use the small ones too – whichever you prefer for your students. 

Create the base. Students will start by forming a semicircle of marshmallows connected with toothpicks. This will be the base of your igloo. The marshmallows should be spaced evenly and connected in a line to form the base foundation.  They should do two layers exactly the same – we used 10 marshmallows for each of those layers. 

STEP 2

Place toothpicks facing up and out of the marshmallows, these will allow you to stack the marshmallows to start to form your igloo.

STEP 3

This layer is key – use 10 marshmallows again, but this time form a full ring.  Stack this layer on the first two, making sure you have toothpicks sticking up by the ends of the first two layers, this will in essence create the entrance to your igloo. 

STEP 4

Repeat making another ring, this time with 8 marshmallows and stack it on top of the others. 

STEP 5

For the top layer we connected 6 marshmallows together in more of a grid and placed it on top to complete our igloo. 

This challenge focuses on the basic concepts of stability and load-bearing structures, using toothpicks to hold the igloo together. Kids will learn how creating a solid base will add stability and distribute weight evenly, making the structure more stable.

Level Up! How to Build an Igloo without Toothpicks

For this advanced challenge you’ll only need marshmallows, patience  and creativity.

The Goal

Build an igloo without the support of toothpicks. This requires kids to think about how to create a stable arch and structure using the marshmallows alone, which can be a bit tricky since marshmallows are soft and tend to collapse under pressure. 

The Process

Remind the kids to start with a strong foundation. Just like in the first challenge, kids should begin by forming a ring of marshmallows to create a strong base. However, this time, they’ll need to think more carefully about how they place the marshmallows to ensure stability as they build upwards.

For example – in the toothpick challenge we laid the marshmallows on their sides – for this challenge it will likely work better to stack the marshmallows on their flat ends. Building the walls as the marshmallows stack, kids will encounter the challenge of keeping the igloo stable without using toothpicks.

They’ll need to experiment with different shapes, angles, and methods to achieve the dome shape.  I can tell you that while testing this out my structure collapsed about 20 times.

The most difficult part of this challenge is creating the arch that forms the igloo’s dome. Kids will learn how to balance materials and distribute weight effectively to keep the igloo from collapsing. They may need to take their time to experiment with different strategies to figure out how to complete the structure.  

This challenge introduces some more complex concepts like compression and tension, and it encourages kids to problem-solve as they figure out how to create a dome shape without external support.

More Classroom Activities with Marshmallows

For more Marshmallow Engineering Challenges check out these STEM projects.

Plus you can have even more fun with Marshmallows including making art

Or do some fun science experiments with marshmallows, including making them with kitchen science!

The Marshmallow Igloo Challenge is a great way to combine winter fun with learning. By building an igloo, kids not only learn about engineering but also get a glimpse into the ingenuity of Arctic cultures. Whether using toothpicks for a simple structure or tackling the advanced version by creating a marshmallow arch, this activity will challenge kids to think like engineers!