This study aimed to determine the effectiveness of using Team Assisted Individualization (TAI) as cooperative learning teaching approach to improve students’ mathematical cognition. A quantitative research design via experimental design using one group pretest and post-test was employed. This only concentrated on specific students’ processing speed and working memory and included 67 grade 9 students from a public school in the Philippines. The findings showed that the components of TAI were moderately effective under the placement test, effective under the teams, (...) teaching group, student creative, team study, fact test and team score than whole class and highly effective under team recognition, Furthermore, there is a significant difference between the pre-test and post-test scores in each completed stage, and TAI approach is an effective strategy in improving the mathematical cognition of students. This study argues that TAI approach may be utilized in mathematics classrooms to improve the mathematical cognition of students. The gravity of the lessons or topics may be put into consideration to balance the learning and performances of students. (shrink)