This research aimed at investigating the effectiveness of STEM approach in developing visual reasoning and learning independence for preparatory stage students. To achieve this aim, the researcher designed a program based on STEM approach in light of the principles of nanotechnology. Twenty one preparatory stage students participated in the research. The researcher applied one-group research design through application of the research instruments to the selected group before the program, administration of the program, and post application of the instruments. This research design is appropriate for educational researches which present new processes in the content of programs or curricula that the students have not previously studied and these processes may take the form of new information, skills, or teaching methods. After data collection and application of the appropriate statistical treatments, the researcher reached the following results: there is a statistically significant difference at the 0.01 level between the students' mean scores in the pre and post-application of the achievement and visual reasoning tests in favor of the post-application. The results of the portfolio assessment of students also indicate the development of the students' ability to take responsibility of their learning, their ability to choose, their confidence, and consequently their competency in the aspects of learning independence.