Students’ understanding and misconceptions of covalent bonding using ball-and-stick molecular models

Abstract

This study investigated the effectiveness of ball-and-stick molecular models in teaching covalent bonding to an O-Level Chemistry class in Gweru District, Zimbabwe. A convergent concurrent mixed-methods design was employed, with quantitative and qualitative data collected simultaneously and analyzed separately before integration. Quantitative data were obtained through pre- and post-tests, while qualitative data were collected using classroom observations and student questionnaires. Students’ pre- and post-test scores were compared using a paired-samples t-test. The results revealed a statistically significant improvement in students’ performance following the use of molecular models (p < 0.0001), indicating a positive effect on their understanding of covalent bonding. Qualitative findings showed that the models supported students in visualizing three-dimensional molecular structures and understanding the arrangement and formation of covalent bonds. However, some students developed misconceptions, including the belief that molecular models perfectly represent real molecules. Open-ended responses also revealed difficulties in understanding electron sharing and bond flexibility. The study concludes that ball-and-stick molecular models are effective instructional tools when their strengths and limitations are explicitly addressed. It recommends integrating guided discussions, formative assessment, and digital modelling with physical models to strengthen students’ conceptual understanding and connections between molecular representations, electron behavior, and chemical symbols.