This study investigated the relationship between a computer-assisted instructional mathematics website used to support classroom instruction and fourth grade students' achievement on MAP, as measured by NWEA. In addition, the study also investigated the relationship between the same computer-assisted instructional mathematics website and fourth grade students' overall growth on MAP from the beginning of the school year to the end of the 2016-2017 school year. A correlational analysis between student usage of the computer-assisted instructional mathematics website, measured in minutes, practicing skills for the duration of the school year, and their end of the year math MAP RIT scores was completed. A correlational analysis was also completed between the computer-assisted instructional website usage and the amount of growth between beginning and end of year RIT scores. The results of this study indicate that there is a weak correlation between student usage and math MAP achievement. Results also show that there is a very weak correlation between student usage and growth in math MAP RIT scores. The findings conclude there are limited advantages to using this particular computer-assisted instructional technology tool for fourth graders when the goal is to increase student achievement and growth in mathematics. [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.]