The purpose of this qualitative exploratory case study was to examine the perceived obstacles that contribute to the achievement gap between White and Black middle school mathematics students and the instructional strategies that help combat these obstacles of middle school mathematics teachers. The study investigated how middle-school educators perceive the difficulties of instructing diverse student populations, the outside factors that exacerbate the teaching experience, and the instructional strategies they use that help underperforming populations make gains on standardized tests. The specific problem is that the South Carolina Ready mathematics tests for middle school students show significant achievement gaps between Black and White students and middle school need to explore what instructional strategies can assist more diverse students in middle school mathematics. Data were collected from six middle school mathematics teachers ranging from grades six through nine in one middle school in South Carolina using online surveys, face-to-face pre- and post-observation interviews, classroom observations, and curriculum artifacts. The collected data were coded and analyzed using NVivo 11 and five themes emerged as contributing to the achievement gap which included Cultural Differences, Varying Prior-Educations, Student Lack of Exposure/Experience, Lack of Parent Involvement/Low SES Background, and Students' Apathy/Lack of Confidence. Seven major instructional strategies emerged as being successful in closing the achievement gap in mathematics classrooms including Progress Monitoring/Data Collection, Graphic Organizers, Personalized Learning/Videos, Collaboration, Manipulatives/Visuals, Interactive Games/Activities, and Discovery. [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.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]