The purpose of this quantitative causal-comparative research was to examine if and to what extent there were differences in students' cognitive load and the subsequent academic performance based on block bell schedule and traditional bell schedule for freshmen in Algebra 1 in the Southwestern United States. This study included students from two Phoenix area high schools enrolled in Algebra 1 during the spring semester of the 2016-2017 school year; one school on a traditional bell schedule and one school on a block bell schedule. This causal-comparative study addressed the two research questions: first, is there a statistical difference among freshman student cognitive load in Algebra 1 measured by Paas' (1992) Nine Point Mental Effort Rating Scale between 90-minute block schedule and 50-minute traditional schedule? And second, is there a statistical difference in freshman student academic performance based on a 90-minute bell schedule in Algebra 1? The statistical analysis showed there is a statistical difference among student cognitive load in Algebra 1 between 90-minute block schedule and 50-minute traditional schedule; t(38) = 2.428, p = 0.020. However, the results also showed that there is no sufficient evidence from the study to support that there is a statistical difference in student academic performance based on a 90-minute bell schedule and 50-minute bell schedule in Algebra 1. The results suggested that there are meaningful theoretical and practical conclusions that may be beneficial to researchers, teachers, schools, and districts for the future of education. [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.]