This worksheet provides practice problems on informal proofs of similarity between two triangles. Part 1 covers a common scale factor, Part 2 a sequence of transformations, and Part 3 covers congruent corresponding angle measures. Examples are provided so students can be more self-directed, and English Language Learners can use those examples as sentence stems. This resource is PARCC aligned and provides ample practice on proving similarity. It is alligned to CCSS 8 Math, but can be used to spiral similarity in HS Geometry or Integrated Math I. I have used this as stations based classwork, as well as homework. Enjoy!