Ask children to examine and discuss their observations of each holiday ornament shape. Have them name the shape of the sides and then count the number of sides and corners on each ornament. Invite children to tell ways in which the two ornaments are similar and different.
Show children the patterns for the pyramid and cube. Explain that the patterns have two dimensions—length and width—so they are called two-dimensional. Then demonstrate how to fold the pattern to create the pyramid and cube. Tell children that these shapes are three-dimensional because they have length, width, and depth. Point out each dimension. Afterward, give children a pattern for each shape and have them construct the three-dimensional shapes. Encourage them to identify each dimension on their completed shapes.