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A study of tertiary chemistry students’ conceptual knowledge in the topics of molecular geometry and polarity
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Type
Thesis
Author
Teh, Yun Ling
Supervisor
Riley, Joseph Philip
Chia, Lian Sai
Subramaniam, R. (Ramanathan)
Abstract
This mixed-methods research study aims to identify the conceptual knowledge of first year chemistry undergraduates in the topics of Molecular Geometry and Polarity. It also investigated the effectiveness and efficiency of various instructional treatments, including small-group discussion, use of leading questions and molecular models, in the context of tutorials. The study was conducted in the two top universities in Singapore. It thus helped to increase the documented data on the conceptual knowledge of chemistry undergraduates, which are still limited in the Singapore and Asian contexts. This study also hopes to draw the attention of curriculum planners, teachers and students from both tertiary and secondary levels on the undergraduates’ current conceptual knowledge, the existence of alternative conceptions as well as the pros and cons of some instructional methods, so as to improve the quality of teaching and learning of chemistry.
To achieve greater depth to the research findings, data were collected using both quantitative and qualitative methods. The quantitative data on students’ conceptual knowledge level and the impact of various instructional treatments were determined by statistical analyses on the concept test scores and confidence ratings. Convenience sampling was used in this research study and the students were non-systematically distributed into the various treatment groups due to logistics constraints. Survey responses on students’ learning experiences with chemistry were another set of quantitative data. Information on students’ conceptual understanding, alternative conceptions, experiences with chemistry and views on the instructional methods were revealed from the semi-structured interviews, which served as the qualitative data.
Although no statistically significant differences were found among the individual instructional treatments, students who experienced any one of the treatment sessions (small-group discussion, use of molecular models and traditional instruction) performed better in the class-test as compared to the control group, who did not attend any of the treatment sessions. Students with average and low pre-test scores also performed better after experiencing any of the treatments as compared to the control group. Students having higher grades in their pre-university chemistry examination performed better in the post-test after they experienced any of the treatments as compared to those having lower grades. Based on the confidence tier results, students were generally more confident when their answers were correct, less confident when their answers were wrong, had higher confidence discrimination and showed close to perfect calibration after the instructional treatments. These data suggest that the instructional treatment sessions had some impact in improving students’ understanding in the chosen chemistry topics.
The instructional treatments were well-received by the interviewees although some of them felt that small-group discussion was not effective. Many previous studies reported that concrete molecular models helped students to visualize molecular geometries and improved their conceptual understanding. However, this study found out that some students resent building such models while some were confused by the representations of the models. Prior research also suggested that leading questions used in a class have merits but found to be not practical in a one-hour tutorial setting in this study. This is because the use of leading questions was time consuming and also the range of students’ conceptual understanding levels was wide.
Most students knew concepts such as Valence Shell Electron Pair Repulsion (VSEPR) theory, Valence Bond (VB) theory, hybridization, molecular geometry and polarity separately but could not apply and integrate these concepts together. This study also identified some difficulties faced by the interviewees in learning these concepts. About one third of the undergraduates were unable to distinguish “linear” and “planar” structures. Some alternative conceptions were also identified during the interviews: (i) the more polar the bond, the stronger it is; (ii) lone-pair electrons on the central atom were electron-withdrawing. These findings have not been reported in other studies.
To achieve greater depth to the research findings, data were collected using both quantitative and qualitative methods. The quantitative data on students’ conceptual knowledge level and the impact of various instructional treatments were determined by statistical analyses on the concept test scores and confidence ratings. Convenience sampling was used in this research study and the students were non-systematically distributed into the various treatment groups due to logistics constraints. Survey responses on students’ learning experiences with chemistry were another set of quantitative data. Information on students’ conceptual understanding, alternative conceptions, experiences with chemistry and views on the instructional methods were revealed from the semi-structured interviews, which served as the qualitative data.
Although no statistically significant differences were found among the individual instructional treatments, students who experienced any one of the treatment sessions (small-group discussion, use of molecular models and traditional instruction) performed better in the class-test as compared to the control group, who did not attend any of the treatment sessions. Students with average and low pre-test scores also performed better after experiencing any of the treatments as compared to the control group. Students having higher grades in their pre-university chemistry examination performed better in the post-test after they experienced any of the treatments as compared to those having lower grades. Based on the confidence tier results, students were generally more confident when their answers were correct, less confident when their answers were wrong, had higher confidence discrimination and showed close to perfect calibration after the instructional treatments. These data suggest that the instructional treatment sessions had some impact in improving students’ understanding in the chosen chemistry topics.
The instructional treatments were well-received by the interviewees although some of them felt that small-group discussion was not effective. Many previous studies reported that concrete molecular models helped students to visualize molecular geometries and improved their conceptual understanding. However, this study found out that some students resent building such models while some were confused by the representations of the models. Prior research also suggested that leading questions used in a class have merits but found to be not practical in a one-hour tutorial setting in this study. This is because the use of leading questions was time consuming and also the range of students’ conceptual understanding levels was wide.
Most students knew concepts such as Valence Shell Electron Pair Repulsion (VSEPR) theory, Valence Bond (VB) theory, hybridization, molecular geometry and polarity separately but could not apply and integrate these concepts together. This study also identified some difficulties faced by the interviewees in learning these concepts. About one third of the undergraduates were unable to distinguish “linear” and “planar” structures. Some alternative conceptions were also identified during the interviews: (i) the more polar the bond, the stronger it is; (ii) lone-pair electrons on the central atom were electron-withdrawing. These findings have not been reported in other studies.
Date Issued
2011
Call Number
QD49.S55 Teh
Date Submitted
2011