Skill: Identify faces, edges, and vertices

A face is a flat surface.
An edge is a line segment where two faces meet.
A vertex is a corner point where edges meet.

Example: Count the faces, edges, and vertices of a rectangular prism.

Imagine a box-shaped solid.

1. Count the faces.
   It has a front, back, top, bottom, left, and right face.
   So, it has 6 faces.

2. Count the edges.
   Each face has line segments around its sides. Count the box’s edges only once:

   • 4 around the top
   • 4 around the bottom
   • 4 connecting the top and bottom

   So, it has 12 edges.

3. Count the vertices.
   A vertex is a corner of the box. Count:

   • 4 corners on top
   • 4 corners on bottom

   So, it has 8 vertices.

Therefore, a rectangular prism has:

$$6\text{ faces},\quad 12\text{ edges},\quad 8\text{ vertices}$$

Remember: a curved surface is not a flat face, and a curved solid may not have straight edges or vertices.