The authors applied a one group pretest-posttest quasi-experimental research design to one section of GVAHS with 45 students to look into the effectiveness of journal writing in mathematics performance consequently preparing the students to technical subjects in the STEM track of the K to 12 curricula. The findings of the study revealed that journals in mathematics produce better and improved scores for students in problem solving tasks. Likewise, journal writing helped the students communicate with their Math Teacher. It can improve their abilities on how to use mathematical tools, symbols and numbers, use math models, analyze, understand and solve problems preparing them for higher mathematics and other related sciences. Also, journal writing helped students to learn how to transfer ideas clearly and convey their feelings and thoughts effectively. Likewise, it enhanced different characteristics that they can use in pursuing the STEM track andin living in the globally competitive world of work.