In their ongoing professional development project, the authors had an opportunity to work with a group of teachers who were particularly insightful. These teachers shared written reflections about their thinking, prior experiences, and changing self-awareness of their mathematics practice. In one session, teachers were provided the "Mathematics Teaching in the Middle School's" November 2015 feature article, "12 Math Rules That Expire in the Middle Grades," by Karp, Bush, and Dougherty (2015). This article presented "rules" that are often taught to students in elementary and middle-grades classrooms, but eventually "expire" in that they often do not apply as students learn more complex mathematics. These rules are often taught as mathematical truths and become the mathematics that students remember without having explored the mathematics behind the rules. This increases the danger of students developing a shallow understanding of mathematical concepts and seeing mathematics as a series of rules to follow. Such rules fail to transfer to more complex mathematics that students encounter in high school, and students are forced to unlearn what they thought to be true. This article describes how this group of teachers used the article "12 Math Rules That Expire," as an impetus to reflect on their experiences as mathematical learners and as teachers of mathematics. The article served as a framework for teachers to consider the limitation of the "rules" they routinely teach.