Tan, Kim Chwee Daniel

Particle nature of matter is one of the most challenging models students encounter in secondary science. Numerous studies have written about the learning impediments and the alternative conceptions that students have while learning to understand and apply the particle nature of matter to explain phenomena such as thermal expansion and phase changes. This article illustrates how some common representations used in science texts and lessons can inadvertently constrain understanding of the particle model and offers suggestions on how students can be better supported in understanding these representations.

Chemical bonding is a topic which many secondary students find difficult to understand. The concepts in chemical bonding are abstract; one cannot see an atom, its structure and how it reacts with other atoms. Therefore there is great potential for the formation of alternative conceptions as students try to derive meaning from what is written in the textbooks or what is said by the teacher. Thus teachers need to be able to detect and diagnose the alternative conceptions of their students so that they can challenge these alternative conceptions, and help the students to acquire scientifically acceptable ones. Methods used to determine students’ understanding of concepts include concept mapping (Novak, 1996), interviews (Carr, 1996) and multiple choice diagnostic instruments (Treagust, 1988, 1995). However, multiple choice diagnostic instruments are more readily administered and scored than the other methods, and thus are particularly useful for classroom teachers. This paper describes the development of a two-tier multiple choice diagnostic instrument to identify Secondary Three and Four students’ alternative conceptions in basic chemical bonding.

This paper draws on Foucault to (a) describe the production of classroom discourse in relation to how ordering manifests within the discourse, and (b) to explicate how chemistry classroom discourses are not fixed but are the site of constant contestations of power as displayed in an eighty minute high school lesson on organic chemistry in Singapore. This microanalysis of discourse provides opportunities to reconstruct how teachers teach and dispels the notion that power is uniquely their sovereign possession. Classroom instruction is in fact a complex activity that coordinates power/knowledge production through communication. Examining classroom instruction through Foucaultian lenses uncovers the taken for granted nature of communication and illustrates the capillary relations of power and knowing.

This research was conducted to investigate students' understanding of fundamental thermal concepts in everyday contexts. The 19 multiple-choice items in the questionnaire used in this study required written justifications for students' choice of responses. The items involving fundamental thermal concepts about heat, temperature, heat transfer and conduction were based on a previously developed questionnaire and from students' alternative conceptions derived from the research literature. The items which were entirely based on everyday contexts with scientific terminology avoided were administered to 80 Year 11 Singapore students. Four or five students from each class were interviewed in order to obtain additional information about their conceptual understanding and to probe the reasons they gave. Analysis of students' responses revealed several alternative conceptions of thermal concepts. Also, even though they held several acceptable scientific conceptions, many students had difficulties in applying thermal concepts in everyday contexts. The findings imply that classroom teaching needs to provide opportunities for students to make connections between scientific concepts and everyday contexts and to develop teaching strategies to help students better understand the related science concepts.

This cross-age study sought to determine the extent of secondary students’ (14-17 years old), junior college students’ (16 to19 years old), and graduate in-service teachers and trainee-teachers’ understanding and alternative conceptions of basic inorganic chemistry qualitative analysis. The results from the administration of the two-tier multiple choice Qualitative Analysis Diagnostic Instrument (QADI) showed that there was a statistically significant difference in mean scores across educational levels – as expected, the in-service teachers and trainee-teachers obtained the best results, followed by the junior college and the secondary students. However, the mean scores of the graduates (9.9/19), junior college students (8.1) and secondary students (5.8) showed that they found the QADI difficult. The cross-age study showed that many alternative conceptions were prevalent among the different groups but were consistently held by only a small number of subjects (0-23%) across all contexts examined in the QADI. These results indicated that the subjects might have more than one conception for a particular concept, or had little understanding of qualitative analysis and resorted to guesswork. The present chemistry practical assessment system in which only students’ written reports are assessed and marks mainly allocated to correct observations could be the major factor influencing students’ lack of understanding of QA.

Chemical bonding is a topic which many secondary students find difficult to understand. The concepts in chemical bonding are abstract, so there is great potential for the formation of alternative conceptions as students try to derive meaning from what is said by the teacher or what is written in the textbooks. Thus teachers need to be aware of students’ conceptions of chemical bonding in order to develop teaching strategies to enable their own students to construct ideas of chemical bonding which are compatible with the scientific concepts.

This paper reports the findings of an online survey aimed at exploring the use of dataloggers in learning inquiry science and project work in secondary schools and junior colleges. It examines the type of activities which teachers conduct using dataloggers, the support structures they deem necessary and the difficulties they faced. Out of the 593 Heads of Department (Science) and science teachers who responded to the online questionnaire survey, 394 (67%) have used dataloggers in the last 2 years, mainly in demonstrations and set experiments. The three most important support structures that were listed by the respondents included: supportive laboratory technicians who were able to use dataloggers, training on the use of dataloggers, and instructional material about how to use dataloggers in the curriculum. The difficulties which deterred the respondents from using dataloggers included the difficulty and time taken to set up the datalogging equipment and activities, insufficient computer workstations, and the mishandling of equipment by students. Recommendations about facilitating the use of dataloggers in school include the setting up of laboratories dedicated for datalogging activities, having courses on datalogging for teachers and laboratory technicians, and the preparing curricular materials on datalogging.

This paper describes the analysis of two commonly used secondary chemistry textbooks and two practical workbooks in Singapore to determine if the contents present are consistent with the concepts and prepositional knowledge, identified by the authors, as essential for the learning and understanding of O-level qualitative analysis. It was found that none of the textbooks and workbooks explicitly highlighted all the reactions involved in the procedures in qualitative analysis. The omission was likely to give students incomplete or little understanding of qualitative analysis, resulting in students adopting a cookbook understanding of qualitative analysis, resulting in students adopting a cookbook approach to qualitative analysis practical work.

This cross-age study sought to determine the extent of secondary students’ (14-17 years old), junior college students’ (16 to 19 years old), and graduate trainee-teachers’ conceptions of the reactions involved in the testing of cations and anions in basic secondary qualitative analysis. The results showed that many of the participants in the study had little understanding of the reactions involved, and that alternative conceptions were prevalent among all groups of participants. The authors believe that the lack of understanding of the reactions involved in qualitative analysis is due to the requirements of the present qualitative analysis practical work assessment system which mainly emphasizes students’ observational skills.

High school students have difficulty in understanding the concepts involved in intermolecular forces. A sound starting point for the teaching and learning of a difficult chemistry topic would be the clarification of the content framework that is required for the topic. Lists of propositional knowledge statements and concept maps should be drawn up to define the content framework for the topic to make explicit the essential concepts of the topic and how these concepts are linked to each other. In this paper, the authors described how the content framework for high school intermolecular forces was developed to facilitate the teaching and learning of intermolecular forces.