Using a ruler, draw a square. On each side find a point that divides the side in 3:1 ratio. Connect the points. What shape did you get ("quarter points" as vertices). What other shapes you can observe inside? Shade any pair of opposite triangles. Repeat the process for the inner square. Shade a pair of opposite triangles that have sides lying on the sides of the previously shaded triangles. Keep doing the procedure until the inner square becomes too small.