The purpose of this action research was to understand the impact of computer-based instructional scaffolding in Desmos on Math 3 high school students' performance and attitudes toward mathematics. The demand for societal mathematics literacy has increased significantly over the last decade and continues to grow. To achieve this literacy, students must reason, augment, communicate, model, and problem-solve with technology applications; development of these skills requires engagement and support through technology-rich learning opportunities. Currently, Math 3 students are not performing at the proficient level on state exams and are displaying negative attitudes towards mathematics. Student attitudes and performance in technology enhanced learning experiences can lead to the development of these aforementioned skills and gains in achievement. This study explored two research questions related to this idea. The first question investigated how the use of Desmos as a computer-based scaffold impacts Math 3 students' performance in mathematics. The second question investigated the impact of Desmos, used as a computer-based scaffold, on Math 3 students' attitudes toward mathematics. This action research employed the intervention of Desmos as a computer-based scaffold to supply supported investigation and dynamic mathematical engagement during a unit of instruction. Desmos is an online application that offers students graphing tools and supplies teachers with pre-built lessons that utilize digitally-enhanced activities. These activities supported learner investigation with prompts, user controlled graphing, multiple representations of mathematical ideas, and reflective engagement. Twenty-five high school Math 3 students participated in the study; 7 participated in student interviews. Pre and post tests along with pre and post surveys supplied quantitative data while student interviews supplied qualitative data. Descriptive and inferential statistics analysis for pre and post data sets occurred through paired t-tests; an increase in scores was noted. Student interviews were analyzed through inductive, thematic analysis. Data analysis reported no change in student attitudes toward mathematics from pre to post intervention. This mixed method approach created a well-rounded perspective of student experiences that supported overall interpretations of study results. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]