Limited studies have been conducted on the relationship between scheduling formats and academic performance of high school students. At the target high school, students underperform on standardized tests in English language arts (ELA) and math. The purpose of this causal comparative quantitative study was to compare the means of ELA and math test scores of students taught via the traditional teaching schedule to those taught via the 4 x 4 block schedule. The research questions that guided this study sought to examine the relationship between 2 scheduling formats and student proficiency as measured by mean state scores on ELA and math standardized tests. The theoretical framework was based on the spacing effect theory, which suggests that more information is retained if taught over longer teaching periods. Data were collected from (a) a convenience sample of 739 students' state scores from the 2010-2011 graduating class that received instruction for 2 years using the traditional schedule and (b) the 2008-2009 graduating class that received instruction for 3 years using the 4x4 block schedule. An independent t test was used to measure the difference in the means of the ELA and math scores for the 2 cohorts. According to the findings, the means of ELA standardized test scores were affected by the use of the traditional teaching schedule; however, the means of math standardized test scores were not affected by either 4 x 4 block or traditional teaching schedule. Implications for positive social change include strategies for high school leaders to use research-based teaching schedules. The use of effective teaching schedules may help students graduate from high school to enter higher education or the workforce. [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.]