Research has suggested the "No Child Left Behind Act" passed in 2001 has resulted in narrowed curriculum and a failed attempt at its primary objective to close the achievement gap. Understanding changes that have occurred in student achievement from 2011 to 2014 of the NCLB requirements is the focus of this quantitative ex-post facto study. Whether change occurred or not in student achievement during this time was analyzed by comparing aggregate average mathematics scaled scores for grades three, five and eight within a southwestern suburban county in the state of Arizona. Additionally, as part of NCLB requirements, Arizona has assigned performance based school labels to the general public called Arizona A-F Letter Grades. This study includes an examination of changes in the Arizona A-F Letter Grades assigned to schools by the Arizona Department of Education from 2011 to 2014. The findings for the research can be summarized under six major themes. The first theme was that student average scaled scores for all students did not show significant change from 2011 to 2014 for third, fifth, or eighth grades. When compared relative to all groups, there were no overall statistically significant changes in average mathematics scaled scores from 2011 to 2014. The second theme was that no statistically significant changes overall were found in mathematics average scaled scores among ethnic subgroups from 2011 to 2014 in 3rd, 5th, or 8th grade in the southwestern suburban county studied. The third theme was that no statistically significant changes overall were found in mathematics average scaled scores among socioeconomic subgroups from 2011 to 2014 in 3rd, 5th, or 8th grade in the southwestern suburban county studied. The fourth and fifth theme, identified through additional analysis, were that when achievement scores were compared together from 2011-2014, substantial achievement gaps remained between all ethnic groups as well as between high-SES and low-SES groups. The sixth theme was that Arizona A-F Letter Grades assigned to schools showed statistically significant growth from 2011 to 2014. Although the results showed small movement, they showed that schools in this southwestern suburban county are making some improvement in overall student achievement during this time. Future research suggestions and implications for current practice are included as a result of this research study. [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/en-US/products/dissertations/individuals.shtml.]