The formula 𝑬 = 𝑭 + 𝑽 – 2 works for pyramids because they are a type of polyhedron. For a triangle-based pyramid 𝑭 = 4, 𝑽 = 4 and 𝑬 = 6. 4 + 4 – 2 = 6.

Now let’s look at the net of another shape. Here is the net of a triangular prism. Can you see that a triangular prism has 5 faces. It has 2 triangle faces and 3 rectangle faces.