Tennessee educational leaders initially implemented Response to Instruction and Intervention for the same reason other states across the nation adopted the framework; to identify students with specific learning disability. In 2014, Tennessee restructured the Response to Instruction and Intervention model to move from the traditional three-tiered model to a model that included teaching and behavior, which focused on instructional opportunities for all students, not solely a pathway to special education eligibility (Berkeley et al., 2020). Tennessee students, regardless of what tier they were assigned, should receive high quality instruction during core extension. I found little existing literature focused on math Response to Intervention and Instruction in rural middle schools. The purpose of this qualitative, interpretive study was to examine certified educators' perceptions of math core extension in rural Tennessee middle schools. I sent a questionnaire to 50 certified educators in varying rural Tennessee school districts. After 25 educators completed the questionnaire, I found participants had similar perceptions of benefits and barriers of teaching math core extension groups. The results revealed benefits of core extension, including increased math scores on end of year assessments, the benefits of working with students in small groups, and the confidence students gained while improving math skills. Results also included barriers to core extension, such as non-math certified educators being asked to lead groups. [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.]