I can use proportions to identify similar polygons.
http://ca.ixl.com/math/grade-10/perimeters-of-similar-figures
Source: www.ixl.com
http://ca.ixl.com/math/grade-10/similar-triangles-and-indirect-measurement
http://ca.ixl.com/math/grade-10/similarity-rules-for-triangles