The purpose of this quantitative, causal-comparative study was to examine the application of the teaching and learning theory of social constructivism in order to determine if mathematics instruction provided in a departmentalized classroom setting at the fifth grade level resulted in a statistically significant difference in student achievement on the Virginia 2011 Grade 5 Mathematics Standards of Learning (SOL) Test when compared to the achievement of students in a non-departmentalized setting. Regular fifth grade education students, who attended non-Title 1, Pre-K through Grade 5 elementary schools in an urban eastern Virginia school district, participated in this study. A three-way between-groups analysis of covariance (ANCOVA) was conducted, utilizing students' Virginia 2010 Grade 4 Mathematics SOL Test scores to control for previous achievement, comparing the mathematics achievement of departmentalized and non-departmentalized whole groups, as well as gender and racial minority/non-minority subgroups. The results of a three-way ANCOVA analysis, which incorporated the factors of classroom organizational structure, gender, and racial status, showed that using a departmentalized setting for instruction resulted in a statistically significant difference in student achievement in mathematics based upon classroom organizational structure. There was not a statistically significant difference in student achievement based upon the effect of gender or race, and additionally, there were no statistically significant interactions between gender, race, and structure, as measured by comparing departmentalized and non-departmentalized whole group and subgroup performance. Therefore, the results of this study suggest that there may be a cause-and-effect relationship between using a departmentalized setting to provide instruction in mathematics at the fifth grade level and higher student achievement in mathematics for all students. [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.]