The paper presents an assessment of the impact of teaching physics using the Inquiry Based Science Education (IBSE) method on the level of competence and knowledge of primary school students in Poland (second educational stage). The method is based on the teacher-inspired teamwork of students to solve experimental physical problems. This results in strengthening students' inquisitiveness, daring to hypothesize, analytical skills and critical thinking. Educational progress was observed during two years of work with two classes of children aged 12-14 years (classes VII -- VIII in the Polish primary education system). The students' level of knowledge was assessed through tests conducted at the beginning and end of the teaching cycle, and the results were analyzed using statistical data analysis. The analysis revealed a significant increase in students' interest in physics, strengthening skills and independence in performing experiments, and increasing cognitive initiative. Importantly, the work on physics classes -- positively influenced the involvement of students in the process of teaching other subjects.