Current policy dictates mathematics teacher must have a deep understanding of the subject toteach it. Many states require a major in mathematics as part of the requirements for certification.There is a lack of research regarding how mathematics learned at the tertiary level is utilized inpractice. Utilizing Ball, Thames, and Phelps (2008) Domains of Mathematical Knowledge forTeaching for specificity, this interpretative phenomenological analysis (IPA) documents howthree purposefully selected middle school mathematics teachers understood tertiary mathematicalknowledge to materialize in practice both directly and pedagogically. Defining "AdvancedMathematical Knowledge" (AMK), as knowledge gained from a major in mathematics, analysisof the data collected through interviews revealed AMK content as not implemented directly dueto its advanced nature. Teachers described AMK as categorically different from the mathematicsthey teach. Teachers' coursework was heavily weighted in pure content courses with little or nocourses to develop pedagogical content knowledge. However, AMK was found to affectteachers' specialized and horizon knowledge.

Teachers found the knowledge gained frompedagogical content courses as relevant and useful in practice. Theory regarding AdvancedMathematical Thinking (AMT) was utilized to understand teachers' perceptions. These findingsare significant for policy makers, teacher preparation program designers, as well as current andprospective mathematics teachers. This study advocates for the formal inclusion of AMT theoryinto teachers' preparation to aid their understanding of it; the study also advocates for moreopportunities to formally develop pedagogical content knowledge.