Enhancing Students’ Critical Thinking Skills Through STEM-Integrated Project-Based Learning Modules: A Quasi-Experimental Study of Vocational Financial Mathematics

Abstract

Strengthening students' critical thinking skills has become an important objective of vocational mathematics education, particularly in preparing learners to solve authentic and interdisciplinary problems. This study investigated the effectiveness of STEM-integrated Project-Based Learning (PjBL) modules in supporting students' critical thinking skills in vocational financial mathematics. A quasi-experimental pretest–posttest control group design was conducted with Year 11 students from a vocational high school in Lampung Province, Indonesia, involving an experimental group (n = 30) and a control group (n = 32). Students' critical thinking skills were assessed using pretest and posttest essay tests, and the data were analysed using normalized gain (N-gain) analysis and the Mann-Whitney U test. The STEM-integrated PjBL modules engaged students in authentic vocational financial projects, including motorcycle installment calculations, loan interest analysis, investment planning, and annuity problem-solving. The experimental group demonstrated greater improvement than the control group, with the mean score increasing from 34.13 to 60.47 (N-gain = 0.588), compared with 33.37 to 47.07 (N-gain = 0.304) in the control group. The difference in learning gains was statistically significant (U = 1.00, Z = -6.782, ). These findings suggest that the use of STEM-integrated Project-Based Learning modules was associated with greater improvements in students' critical thinking skills and provide practical evidence for mathematics teachers seeking to implement contextual STEM-integrated project-based learning in vocational financial mathematics.