Journals provide a history of each student's thinking over time and allow this history to be easy to review. Journaling in mathematics has been found to be a valuable tool both for students and for teachers. Students benefit from journaling because it advances their mathematical understanding and ability to communicate in mathematics; teachers benefit by reading students' written thoughts, a resource that is not readily available, and by engaging with students through written feedback (Albert and Antos 2000). In this article, the author sought to use journaling to further develop reasoning and sense making (CCSSI 2010; NCTM 2010, 2014) through teacher and student responses to each other in journals. In so doing, the author also wanted to promote students' critiques of one another's thinking and written mathematical discourse.