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Geometry Activity with Marshmallows

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Finding simple, but stimulating STEM activities for middle schoolers can be difficult.

If you have been struggling, you’ve come to the right place.

This geometry STEM activity is a marshmallow challenge that kids won’t be able to resist! 

A shape built with toothpicks and marshmallows for a Marshmallow Geometry Shapes Activity - MamaTeaches

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Whether you are teaching your lesson in a classroom, through a computer screen, or in a homeschool setting, this building activity will be great to discuss the very basics of geometry. 

Prior to building you will want to discuss four important concepts with your students.

They will need to hear what a 3-dimensional shape is and how it is different from a 2-dimensional shape.

From there, you can touch on the concepts “edges”, “vertices”, and “faces”. 

Before you know it, your students will be mathematicians!

At least in the realm of building 3-D shapes with marshmallows and toothpicks. 

Geometry with Marshmallows - a Geometric Shape Built out of toothpicks and mini-marshmallows


As mentioned above, this activity would be a great add-on to a geometry lesson.

Its hands-on aspect will narrow kids’ focus on what they are learning about.

Ready to get started?

First things first, you will need to gather all of the materials you need.

You don’t need much, which makes this activity even better.

Below is a short list of supplies that can be used by each kid.

So, be sure to multiply the materials by the number of kids that will be joining in for the activity. 

What You’ll Need: 

  • 5 marshmallows
  • 8 toothpicks 


  1. Attach four marshmallows and four toothpicks to form a square. The marshmallows will serve as the vertices and the toothpicks will form the sides. 
  2. Attach a single toothpick vertically to each of the four marshmallows. 
  3. Carefully, pinch the tips of those vertical toothpicks together and stick a marshmallow to form the top vertex. 
  4. There you have it, a pyramid has been formed! 
Marshmallow STEM Activity using a bowl of marshmallows and toothpicks to create a three dimensional geometric shape.

Multiple geometric shapes

What’s great about this activity is you will be able to branch off from it too.

Gather more marshmallows and toothpicks and see if your students can design other kinds of shapes.

You can challenge them by telling them to build a triangular prism or a cube without giving them any more instructions. 

We want to hear how you liked this STEM activity!

Tag us on Instagram @MamaTeaches and share your students’ creations!

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