# Solid Geometry Using Milk Straws

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## Introduction: Solid Geometry Using Milk Straws

This is a quick and easy to make large geometric structures. The only limitation is they have to be made out of triangles. Squares will just flop about!

You will need:

Milk straws.

Cotton.

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## Step 1: Thread the Straws.

The shapes are made by threading cotton through the straws an to make triangles which you link up to make solid shapes.

There are two ways to do this

1. use a darning needle

2 suck the thread through the straw (but be careful not to swallow it.) see above.

Start building up the net (see next step)

## Step 2: Nets

A net is a flattened two dimensional pattern which you fold up to make a three dimensional object. There are plenty of websites you can get this information from.

## Step 3: Solid Geometry

The three shapes here are (from left to right).

1. A tetrahedron. - 4 faces

2. An Octahedron - 8 faces

3. An Icosahedron - 2 faces

https://en.wikipedia.org/wiki/List_of_uniform_polyhedra

https://en.wikipedia.org/wiki/Euler_characteristic

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