Prisms are 3D objects with a constant cross section. Pyramids are 3D objects with a flat base and which taper to a vertex. Many three-dimensional objects can be constructed from 2D nets.

Two-dimensional (2D) shapes are completely flat. They cannot be picked up. 2D shapes can be found printed in a book or you can draw them on a piece of paper. 2D shapes have sides and corners (also ...