In this study, the effects of teacher assistants' collaborative learning and learners' self-assessment on self-regulation and academic achievement at high levels have been investigated. Collaborative learning teaching method (Jigsaw and teacher assistant) is used for one group and the other group had also the same as well as learners' self-assessment for eight 90-min sessions. The study population included 75 persons who are divided into three groups of 25 subjects (two experimental groups and one control group). Using a learning techniques questionnaire and the motivated strategies for learning questionnaire (MSLQ) as well as a self-developed achievement test to measure the geometry in the lower and upper levels of the cognitive domain, it was revealed that "cooperative learning and self-assessment" have a positive effect on promoting learners' "self-regulation" knowledge for geometry course. Collaborative learning and self-assessment also have a positive impact on academic achievement at low land high levels of learners' cognitive domain.