The primary objective of this research was to investigate the effects of model-based science instruction on the conceptual development of 7th grade students in the topic of electricity. This qualitative research was conducted during the 2022-2023 academic year, using purposive sampling method. The study comprised 33 7th grade students (18 boys and 15 girls) from a secondary school located in the city center of the Aegean Region. Students' conceptions were introduced as a conceptual framework representing individuals' mental models. In the study, a conceptual understanding test consisting of five open-ended questions was developed as a data collection tool within the framework of the related literature and science curriculum. In order to evaluate the effects of the designed learning environment, this achievement test was administered to students before and after the instruction. Rubric was used in the analysis of the obtained data. Analyzes were carried out by one researcher and their accuracy was checked by another researcher. The effectiveness of the learning environment is based on the comparison of the pre- and post-test findings. The implementation process lasted 12 lesson hours. The data were analyzed descriptively and classified according to their conceptual knowledge levels. Conclusively, the study demonstrated that the implementation of model-based lessons within the 'Electric Circuits' unit had positive impact on the conceptual development of 7th grade students. In addition, model-based learning sequence reduced misconceptions of students about the topic of electric. Based on these results, model-based teaching was recommended to teachers in the instruction processes and researchers were recommended to investigate features of models and the nature of modeling, the relation between students' knowledge about modeling and the quality of the models they create. [This paper was published in: "EJER Congress 2023 International Eurasian Educational Research Congress Conference Proceedings," Ani Publishing, 2023, pp. 520-537.]