This study aims to report the effort on teaching vector algebra using free open source software (FOSS). Recent studies showed that students have difficulties in learning basic physics concepts. Constructivist learning theories suggest the use of visual and hands-on activities in learning. We will report on the software used for this purpose. The effect of FOSS on students understanding of vector algebra was determined by a non-equivalent control group design. A total number of 113 freshman students from two classes of introductory level physics courses were involved. The experimental group's students learning processes were supplemented by instruction utilizing FOSS while the control group was taught in traditional manner. A significant difference in students' performance was found that could be attributed to the treatment. Consequently, visualization of vector and related concepts by FOSS simulations helped students to understand them well and contributed to shorten the time needed to learn these concepts.