ABSTRACT Background Of many innovative laboratory approaches in the literature, POE (Predict-Explain-Observe) and PDEODE (Predict-Discuss-Explain-Observe-Discuss-Explain) based laboratories approach have been frequently used to enhance laboratory studies during the last ten years. We contend that excluding the discussion phase before the observation stage in PDEODE could be more suitable when applied to science laboratory settings. Consequently, we chose to employ the PEODE (Predict-Explain-Observe-Discuss-Explain) approach in lieu of PDEODE to enhance laboratory-based studies. Purpose The purpose of this study was to investigate effectiveness of PEODE-based laboratory activities in promoting prospective science teachers’ (PSTs) conceptual understanding about fundamental concepts. Sample The quasi-experimental study is based on 46 third grade PSTs in the primary science education department. In the study, randomly selected two groups were used, one experimental group (EG; n = 22) and one control group (CG; n = 24). Design and methods To achieve this aim, we selected fundamental science concepts that students have difficulty in sound understanding and often hold alternative conceptions based on the literature. While the CG participated in traditional laboratory activities, the EG took part in PEODE-based laboratory activities. Laboratory activities were carried out in both groups for a total of 18 hours. In order to assess PSTs’ conceptual understanding about fundamental concepts, a concept test (CT) including 22 test items (two-tiers and open-ended) were presented to them as pre- and post-test. The PSTs’ pre- and post-CT scores was analyzed qualitatively and quantitatively. Results The study overall demonstrated that PEODE based laboratory activities have a significant impact on enhancing PSTs’ conceptual understanding of the fundamental science concepts. Conclusion The PEODE based laboratory employed in this study, introduced as a novel contribution to the literature, demonstrates its potential to facilitate conceptual change.