The solid at right is a regular octahedron.  

1. Trace the shape on your paper. How many faces does it have? How many edges? Vertices?

   Answer (a):

   $8$ faces
   $12$ edges
   $6$ vertices

2. If an octahedron is sliced horizontally, what shape is the resulting cross-section?

   Hint (b):

   It is a type of parallelogram.