This thesis identifies various instructional practices successful intermediate math teachers use to achieve positive gains in mathematics achievement data. After identifying the study group using state assessment data, a direct-data type survey was given online and the results analyzed. Based on the results of the survey data, a classroom observation data collection tool was designed and used to identify instructional practices used by effective teachers. Students in study group classrooms were also given a survey to investigate which practices were most important for their learning. A comprehensive literature review was conducted to define research-based best practices in mathematics and support the findings. The knowledge gained from this study can inform teachers' instructional practices in math, resulting in improved student learning and performance. A list of effective instructional practices that are not only research-based, but tested by classroom practice has been produced using the findings of the study.