The aim of research was to verify the effectiveness of implementing the inquiry-based teaching (IBT) into the teaching process of chemistry in secondary school in the phase of revising and deepening the previous-year learning content. The results of the research confirmed a significant difference on the level of knowledge and skills between the experimental group students (N=143) where the IBT was implemented and the control group students (N=149) where traditional teaching methods were implied. [For the full proceedings, see ED619611.]