Abstract: This study is part of a funded research that investigates the relationship of adolescents’ ethnicity, academic achievement, and mathematics achievement with their perception and processing of the information and their brain functioning. One approach to the study of the normal brain forms the sub-field of neuropsychology called laterality. This particular paper looked into the adolescents’ mathematics achievement against the backdrop of current brain research. It observed the subjects’ underlying patterns of cognitive processing as identified by their brain functioning performance in lateralization tests. Lateralization tests are used to assess subjects’ performances on specialized cognitive functions in relation to their tendency towards performing tasks associated with the right and left hemisphere processes.