Threshold Concepts of Acids-Bases
Description
This study seeks to explore the teaching and learning of acids-bases as threshold concepts (TCs) by chemistry educators. The study investigates how and where lecturers of first-year students were experiencing difficulties in teaching threshold concepts in the curriculum. There are three major threshold concepts in acids-bases, the Arrhenius, Bronsted-Lowry and Lewis concepts. The balancing of chemical equations, writing of ionic equations and acids-bases equilibrium in Arrhenius are TCs. In The key or TCs are the transfer of electrons, ionic bonding and atomic structure. Students need to master acids-bases chemistry from this dimension after which students’ progress to mastering weak acids and bases, constants of acids and bases, finding of pH and pOH values, conjugating acids and bases, neutralisation, buffer solutions, and acids-bases chemical equilibrium which are connecting ideas in the three definitions. Teaching threshold concepts is fundamental to students’ learning of chemistry, which also transforms the learning of chemistry, without which chemistry educators will not be able to teach students effectively. TCs of acids-bases chemistry are related to other topics in chemistry, as in other science disciplines, which the lecturer and students must learn and master. The understanding of TCs and their connections influences the approach to teaching acids-bases. By focusing on students’ learning of TCs, educators (lecturers) can maximise teaching and learning and student’s achievement in the classroom (Meyer & Land, 2003). Educators are aware that acids-bases are taught at secondary school level and that students bring these concepts into higher education. Chemistry educators should teach and learn acids-bases as threshold concepts so that they are able to impart this knowledge to students. Qualitative research methodology was employed because it assisted me to immerse fully in a range of data. In qualitative research, the researcher aims to acquire first-hand knowledge of the sociocultural setting. Action, case-study and phenomenology research designs were employed. Five (5) first-year chemistry educators completed the questionnaires. Then, I had in-person interviews with the educators. Furthermore, classroom observations were guided by the lecturer’s presentation of the key concepts in acids and bases, her/his interactions with the students, students’ activities with each other and the key concepts. A conversation was held with each educator to review the lessons by watching some segments of the video-recorded lessons. In addition, a total of 47 students from the sampled classes, which were taught by each of the five sampled lecturers, were interviewed. Educators’ and students ’activities were video-recorded. The participants were purposively sampled. Qualitative data were coded and presented in the form of themes, categories and narratives.
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In this study, I used quota and purposeful sample techniques to identify the research context and research participants. In purposeful sampling, cases or participants are included in the sample because they believe that they should be there. Pseudonyms were given to research participants to protect their identities. The main participants in this research were chemistry lecturers and first- year chemistry students. I present how they were selected and how data were collected. A purposive sample was chosen to reveal the challenges students/lecturers experience and how they can be ameliorated. There are about 350 students per class and six classes, giving a total of 2,100 students. The first-year chemistry students are grouped from “A” to “F”. The sample size was forty-seven (47) of first-year students who signed consent forms and participated in focus-group interviews. The draft instruments were standardised and validated. Ethical clearance was sought, and permission was granted to pursue the research. On the first round of data collection, information sheets and consent forms were distributed to chemistry educators requesting for their collaboration in the research. I delivered questionnaires to the educators by hand. The responses from the questionnaires were analysed. This was followed by semi-structured interviews for first-year educators in December 2018 and January 2019. In January 2019, a workshop was organised for all chemistry educators based on the results of the questionnaires and semi-structured interviews. Second round data collection on classroom observations and student focus group interviews was in March and April 2019. Students voluntarily signed consent forms and information sheets to research with me. Also, I viewed the clips with each lecturer from their lessons and had conversations according to the research questions at times that were convenient for them.