Threshold Concepts of Acids-Bases

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.