In a previous article, "The Shape of Reasoning: Using Geometry to Promote the Reasoning Proficiency Strand" (EJ1286217), the author put forward the argument that no medium is more powerful than geometry as a vehicle for developing the mathematical proficiency strand of Reasoning. Because geometry is so visual and tactile, the manipulation of materials allows the students to make their thinking manifest, and in doing so gives them the opportunity to hypothesise, conjecture, justify and generalise. Educators need to provide the students with engaging activities in order to exploit these opportunities. Activities which can make students reflect and think deeply are needed. In this article, the author will expand on the reasoning the children started to develop through looking at triangles, and use that to create connections to reason and foster other geometric understandings. The author shows how the use of engaging activities with Pattern Blocks can help students to develop mathematical reasoning.