Introduction: In the proposed study, the authors focus on the effectiveness of the application of inquiry-based approach in Slovak schools and present the results of an original research study focused on the impact of inquiry-based teaching on students' knowledge acquisition. Methods: For the purposes of the research study, a pedagogical experiment was carried out on the sample of 150 6th-grade students and didactic tests (a pre-test and a post-test) were used to examine students' knowledge on the three levels of Niemierko's taxonomy. Results: The results of the t-test confirmed the significance of differences between the experimental group's and the control group's cognitive performance. Discussion: The obtained results indicate that inquiry-based teaching can lead to better knowledge acquisition in students than traditional methods of teaching and so, it appears to be an efficient alternative. Limitations: The limits of the research study are given by the size and the composition of the research sample. The obtained results cannot be generalized to the entire population. Conclusions: The research findings can contribute to improving the quality of the educational process and increasing students' motivation by using activating methods of teaching.