This study aimed to explore the influence of inquiry-based science education (IBSE) in eliciting learner understanding of the particulate nature of matter (PNM) in the gaseous phase. A comparison of the lecture method and the IBSE method was done to identify their effects on enhancing learner understanding on the mentioned difficult science topic. A qualitative pre-test/post-test case study was carried out at two schools in Pretoria, South Africa. Two grade 4 classes were identified at each of the two schools. One of the classes in each school was set aside for lecture teaching and the other was set aside for inquiry teaching. All four classes were initially given a pre-test on the PNM in the gaseous phase. Soon after the pre-test the first group interviews were conducted. At each school one class was then taught using the IBSE method and the other using the lecture method. Soon after the intervention, a post-test was administered to the learners followed by the second group interviews.
Analysis of the pre-test and the first group interview indicated that the initial understanding of learners for both the lecture group and the inquiry group was homogeneous. The continuous model of matter in the gaseous phase emerged as the most prominent view for both the inquiry and lecture group. The results from the post-test and second group interview suggest there was an improvement in particulate understanding in the inquiry group rather than in the lecture group. This seemed to indicate that IBSE was more effective in eliciting particulate understanding as compared to the lecture method