Studies have shown an association between argumentative discourse in science class, better understanding of science concepts, and improved academic performance. However, there is lack of research on how argumentation can increase student motivation. This mixed methods concurrent nested study uses Bandura's construct of motivation and concepts of argumentation and formative feedback to understand how teachers orchestrate argumentation in science class and how it affects motivation. Qualitative data was collected through interviews of 4 grade-9 science teachers and through observing teacher-directed classroom discourse. Classroom observations allowed the researcher to record the rhythm of discourse by characterizing teacher and student speech as teacher presentation (TP), teacher guided authoritative discussion (AD), teacher guided dialogic discussion (DD), and student initiation (SI). The Student Motivation Towards Science Learning survey was administered to 67 students before and after a class in which argumentation was used. Analysis of interviews showed teachers collaborated to plan argumentation. Analysis of discourse identified the characteristics of argumentation and provided evidence of students' engagement in argumentation in a range of contexts. Student motivation scores were tested using Wilcoxon signed rank tests and Mann-Whitney U-tests, which showed no significant change. However, one construct of motivation--active learning strategy--significantly increased. Quantitative findings also indicate that teachers' use of multiple methods in teaching science can affect various constructs of students' motivation. This study promotes social change by providing teachers with insight about how to engage all students in argumentation. [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.]