This study aimed at improving the activities and achievements of students learning. This research is a Class Action Research which was done in three cycles. Based on the result of data analysis, it shows that the student learning activity score of cycle I until cycle III and category in a row are “14,897â€, “19,583â€, and “20,710†with category are “fairly activeâ€, “activeâ€, and “very activeâ€. The result of data analisys of learning achivement, the average score, mastery learning, and absorptive ability of cycle I until cycle III in a row are “7,67â€, “7,77â€, and “8,25â€; “53,85%â€, “71,05%â€, and “89,74%â€; and “76,7%â€, “77,7%â€, and “82,5%â€. The result of data analisys of implementation of the learning of cycle I until cycle III and category in a row are “79,54%â€, “93,175%†and “100%†with category are “goodâ€, “very goodâ€, and “very goodâ€. While for result analisys data of student response, achieving very positive category with an average score of responses student “32,13â€. Thus, the application of cooperative learning type TGT in learning the math flat side geometry can improve the activities and achievements of students learning.