4.G.A.3
Recognize a line of symmetry for a two-dimensional figure as a line across the figure such that the figure can be folded along the line into matching parts. Identify line-symmetric figures and draw lines of symmetry.
First, students will see examples of bilateral symmetry in nature, and other lines of symmetry in nature, such as lines of symmetry in starfish. Recognize bilateral symmetry in nature. Recognize lines of symmetry by folding paper and using mirrors. Identify bilateral symmetry and draw the line of symmetry.