Marshmallows, Sticks & Shapes

Recently, my son was learning about polyhedrons in school and he had to construct 3D models of them. He used toothpicks for the edges and mini marshmallows for the vertices.

The photo above shows an octahedron that he built. He also constructed a cube, tetrahedron, square pyramid, icosahedron, cuboctahedron, and dodecahedon.

Some polyhedrons are pyramids while others are prisms. Can you tell the difference between them?

A pyramid has a flat base and flat sides that converge at a central vertex point at the top (eg, tetrahedron, square pyramid) while a prism has parallel and congruent faces on all sides (eg, cube, icosahedron). The photos below show a tetrahedron pyramid and a cube prism, respectively.

As the shapes became larger, it was more difficult for the structure to hold together. With this modeling method, we learnt that the smaller the shape of the face, the sturdier the structure stood. You can see in the photos below that the icosahedron with triangle faces was sturdier than the dodecahedron with pentagon faces that didn’t seem all uniform.

                 

This was such a fun hands-on math art activity that I had to share, so you can try it too! Also an excuse to snack on marshmallows ;)

If you don’t have marshmallows, you can also use play dough or plasticine for the vertices. With this method, I’m sure you can also build chemistry molecule structures!

There is something so fascinating about polyhedrons. I am especially fond of the platonic polyhedrons, which are the 3D shapes with all identical faces. There are only five of them in the world: cube, tetrahedron, octahedron, icosahedron, dodecahedron. Four of them are featured in the Geometric Shapes Coaster Set.

What is your favorite polyhedron? Have you ever built 3D shapes or molecules? What materials did you use? Tell me in the comments below and I would love to see your creations.

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