Exponential functions are an integral component of the secondary mathematics curriculum with which students struggle. Inherent difficulties students have had around the topic of exponential functions suggested a need for thinking about and examining the teaching and learning related to this content. This study presented the mathematical ideas made possible to learn during instruction related to exponential functions in two College Algebra courses offered at the high school level. Using the variation theory of learning (VTL) as an analytic lens along with thematic analysis, instructional themes, purposes, overarching ideas, and sub-ideas were identified within and compared across two teachers. The cases provided examples of what was made possible to learn around exponential functions in everyday mathematics classrooms, which has implications for research and practice related to the quality of mathematics being offered to students. Additionally, the usefulness of VTL when analyzing instruction presents opportunities for integration with current observation protocols to strengthen the link between teacher quality and student achievement suggested VTL might be beneficial for supporting the development of mathematics teachers. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]