Self-talk is the outcome of a developmental process. It has been studied almost exclusively in children but as they grow older, self-talk is being internalized to them. Addressing the need for self-talk to the students in the classroom and by their age when self-talk is largely internalized, this study investigated how self-talk would be related to mathematics achievement especially to the 4th-grade students. The findings reported in this paper are based on the data from self-talk inventory questionnaires completed by nine-to-ten-year-old, and mathematics achievement test results. Based on previous research, the results were unexpected. Gathered data of the students were analyzed, including that self-talk is still being used by the 4th-grade students, yet no relationship was found with their performance.