Engaging kids in STEM activities has never been more exciting, and easy! We love hands-on building activities for kids, and here’s a great way to build, and teach kids about 3D shapes. Grab some toothpicks and a pack of marshmallows, and our free printable toothpick and marshmallow shape cards below for hands-on geometry for kids!


What Is STEM For Kids?

STEM stands for science, technology, engineering, and math, and activities involving these fields have a huge impact on kids. Even the simplest STEM activities like this printable shape building challenge provide numerous opportunities for kids to learn and explore STEM.

It might look like your kids are just playing, but they are doing oh so much more. Look closely, you will see the design process in motion. You will see experimenting and critical thinking in action, and you will notice problem-solving at its finest.  When kids play, they learn about the world around them!

Take this STEM activity, building 3D shapes with marshmallows and toothpicks. Building structures with toothpicks and marshmallows presents challenges that require creative problem-solving, and enhance critical thinking skills.

It offers an easy gateway into the world of STEM for kids. Through creativity and hands-on exploration, children can develop essential skills that will serve them well in future endeavors. So, grab those toothpicks and marshmallows, and let the engineering adventures begin!

Helpful STEM Resources To Get You Started

Here are a few resources that will help you introduce STEM more effectively to your kiddos or students and feel confident yourself when presenting materials. You’ll find helpful free printables throughout.

What shapes will kids build?

Kids can create simple 2D shapes like squares, triangles, and rectangles, or venture into the world of 3D shapes with pyramids, cubes, and prisms. Here are the main shapes…

Two Dimensional Shapes

Square: A square is a four-sided shape that has equal-length sides forming right angles.

How To Make It: Connect four equal-length toothpicks at right angles using marshmallows at the corners to create a square.

Triangle: A three-sided shape with three angles, and the sum of these angles equals 180 degrees.

How To Make It: Connect three toothpicks to form a triangle by securing them together at each corner with marshmallows.

Rectangle: A four-sided shape with opposite sides of equal length and all angles at 90 degrees.

How To Make It: Create a rectangle by connecting four toothpicks, making sure that the opposite sides are equal in length. Secure the corners with marshmallows.

Pentagon: A five-sided shape with with all sides of equal lengths and five angles.

How To Make It: Form a pentagon by connecting five toothpicks and securing them at each corner with marshmallows.

Three Dimensional Shapes

Pyramid: A pyramid is a three-dimensional shape with a polygonal base (has straight sides and angles) and triangular sides that meet at a common point called the apex.

How To Make It: Construct a pyramid by creating a square base using toothpicks and marshmallows, then connecting additional toothpicks to form triangular sides meeting at a central point.

Cube: A cube is a three-dimensional geometric shape with six square faces, all of which are equal in size.

How To Make It: Build a cube by connecting twelve toothpicks to form the edges of the cube and securing the corners with marshmallows.

Rectangular Prism: A rectangular prism is a three-dimensional shape with six rectangular faces, where opposite faces are equal in size.

How To Make It: Construct a rectangular prism by connecting twelve toothpicks to form the edges, and secure the corners with marshmallows.

Pentagonal Prism: A pentagonal prism is a three-dimensional shape with two pentagonal bases and five rectangular sides.

How To Make It: Create a pentagonal prism by forming two pentagons using toothpicks as bases, and connecting the corresponding vertices with additional toothpicks and marshmallows to create the sides.

How To Use These Shape Cards For Different Ages

  • Preschoolers (3-5 years): Focus on simple shapes like squares and triangles. Give kids opportunity to simply create and play with the structures.

Check out our list of 25 shape activities for preschoolers and kindergarten.

  • Elementary School (6-11 years): Introduce more complex shapes and encourage teamwork. Discuss basic engineering principles like stability and balance.

Working with others to create complex structures promotes teamwork and teaches kids the importance of communication and cooperation.

  • Middle School (12-14 years): Challenge students with more intricate designs and discuss the science behind the structures. Explore concepts like load distribution and structural integrity.

TIP: Kids can let their imaginations run wild as they design and build unique structures, fostering creativity and innovation.

Get your free printable toothpick and marshmallow shape cards!

Print and laminate these shape cards so you can re-use them again and again!

More Fun Building Activities

Develop those design and engineering skills with more easy hands-on building activities. Click on the activities below to find out more.

Marshmallow and Toothpick Challenge

A fun challenge to follow on from building 3D shapes with marshmallows! Use those marshmallows and toothpicks to build the tallest tower. Any shape allowed!

Strong Paper Structures

Experiment with folding paper in different ways to test its strength, and learn about what shapes make the strongest structures.

Strong Paper Challenge

Straw Boat Challenge

Design a boat made from nothing but straws and tape, and see how many items it can hold before it sinks.

Penny Boat Challenge

Design a simple tin foil boat, and see how many pennies it can hold before it sinks.

Penny Boat Challenge

Strong Spaghetti

Get out the pasta and test our your spaghetti bridge designs. Which one will hold the most weight?

Gumdrop Bridge

Build a bridge from gumdrops and toothpicks and see how much weight it can hold.


Printable STEM Pack for Kids

80+ Doable Engineering Projects in one convenient pack!

  • Full instructions with sample images
  • Activity-specific instruction sheets
  • Data Collection Sheets
  • Questions for Reflection
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  • Great marshmallow challenge: A classic challenge kids love!
  • Real-world STEM challenge lesson but don’t know where to start? Our easy-to-follow template shows the steps!
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  • Crossword and word search with engineering vocabulary.
  • Engineering vocabulary cards
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