Two-dimensional (2-D) shapes are all around you. There are regular and irregular 2-D shapes, which are both used in art including sculptures, mosaics, and paintings. One special pattern is a tessellation, which has shapes that fit together with no gaps in between. Many pieces of artwork and architecture use lines of symmetryone side is exactly like the other. Another special pattern is a tangram, which is a puzzle in which there are different shapes that form a square.