Teachers want and need students to excel in the classroom. Cooperative learning is one method recognized to address this. Numerous researchers have shown that cooperative learning leads to improved skills in teamwork and communication in other fields (Johnson and Johnson, 2007; Slavin, 1995). Cooperative learning used in this study showed that the secondary math students benefited socially and academically through effective student communication. This case study reported observational evidence concerning the patterns and experiences of student interaction in discussions within cooperative learning groups in several high school geometry classes. Developed from data collected in observations, audiotapes, and student journals/notebooks, a multiple-case study was used to examine the discussions of two groups of students in cooperative learning groups. Each group participated in three activities: Placemat, to build team camaraderie; Numbered Heads, to strengthen positive interdependence; and STAD, to ensure individual accountability. Four patterns emerged when examining the data: change in attitude toward cooperative learning, the development of trust, group regulation, and the facilitation of math learning. Students showed a more positive feeling toward cooperative learning, stated an increased appreciation for cooperative learning, developed trust in their group members, and were able to analyze what they were doing well and what areas needed work. Math learning occurred when the students demonstrated how they solved problems by communicating using mathematical concepts and language. [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.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]