This research aims to study and compare students' creative problem-solving ability and the quality of students' creative products before, during and after the study in STEM education with the emphasis on the engineering design process. This research is an experimental One-Group Repeated Measures design, with the target groups being 72 junior high school students. The data collection tools used are (1) a creative problem solving competency test with a validity of 0.817 and (2) an evaluation form for the quality of creative products with a validity of 0.993. The data were analysed using arithmetic mean, standard deviation and repeated measures ANOVA. The research findings are as follows: (1) The difference between students' creative problem-solving ability measured after the study and their creative problem-solving ability measured during the first and second study as well as before the study was statistically significant at the level of 0.05, with the level of ability being high; and (2) the difference between the quality of students' creative products after the study and that during the first study and before the study was significantly significant at the level of 0.05. The quality of the products was good.