This study addresses how the flipped method of classroom instruction differs from traditional classroom instruction when comparing student achievement measures in middle and high school mathematics classrooms. The flipped classroom is defined by the Flipped Learning Network (2014) as an instructional method that moves direct instruction outside of the classroom in order to make room in the classroom for a more interactive learning environment where students can actively engage in the content. The flipped classroom strategy theoretically allows teachers the time to develop mathematical ideas and the ability to facilitate that development. For the Common Core State Standards initiative to be effective, teachers need to engage students in new learning experiences that support college and career readiness. By implementing a technology based instructional approach, like the flipped classroom strategy, teachers are able to blend twenty-first century skills with the development of the essential habits of mind of mathematically proficient students (Brunsell & Horejsi, 2013). This study seeks to understand how the flipped method of classroom instruction can lead to improved student achievement in mathematics courses and improve student perceptions about math in order to encourage course consumption in the future (Zollman, 2011). A modified explanatory sequential mixed methods design was used, and it involved collecting quantitative data and then explaining the quantitative results with in-depth qualitative data. In the quantitative phases of the study, NWEA Mathematics MAP Assessment data were collected from middle school students and course common final assessment scores were collected from middle school and high school students in a large Midwestern suburban school district to determine how student math achievement was impacted for students in a flipped classroom as compared to a traditionally instructed classroom. The frequency of active learning incidents was also collected during classroom observations. The qualitative phase was conducted as a follow up to the quantitative results to help explain the quantitative results. In this exploratory follow-up, student and teacher perceptions of mathematics achievement as a result of the flipped classroom approach to instruction with middle and high school math students and how those perceptions might be different than those of students and teachers in traditionally taught classrooms along with descriptions of observable active learning incidents in the school district were explored.