Teachers’ understanding of the particulate nature of matter: The case of Zambian pre-service science teachers

Research studies on chemistry conceptual knowledge indicate that both teachers and students do not have sound understanding of some fundamental concepts that form the basis of the discipline such as atoms and molecules (Nakhleh, Samarampungavan & Saglam, 2005), conservation of matter and chemical equations (Haidar, 1997), chemical equilibrium (Bergquist, & Heikkinen, 1990), particulate nature of matter (Gabel, Samuel & Hunn, 1987; Nakhleh, et al., 2005), chemical bonding (Nicoll, 2001; Ozmen, 2004) and electrochemistry (Sanger & Greenbowe, 1997). However, the particulate nature of matter stands out to be one of the most difficult concepts for teachers and students to understand (Gabel, Samuel, & Hunn, 1987; Valanides, 2000a; Valanides, 2000b; Nakhleh, Samarampungavan & Saglam, 2005; Ozmen & Kenan, 2007). Yet, the particulate nature of matter provides a basis for understanding the invisible microscopic events underlying natural phenomena (Valanides, 2000b). As such, there is a consensus among chemistry educators that the particulate nature of matter is fundamental to understanding other chemical concepts (Tsai, 1999; Boz, 2006; Yilmaz, & Alp, 2006). For example, teachers or students with poor knowledge about the particulate nature of matter are likely to have difficulties to understand kinetic theory of matter, chemical kinetics, and phase changes.

Several studies have examined and reported students’ and teachers’ knowledge about the particulate nature of matter. For example, Boz (2006) reported that middle and high school students had difficulties in applying the particulate nature of matter theory to explain phase changes, even after instruction. Similarly, Ozmen and Kenan (2007) found low levels of understanding about the microscopic properties of matter among students in grades 4 to 6. Nakhleh et al. (2005) compared middle school students’ ideas about the particulate nature of matter to those of elementary school students. The results showed that most middle school students knew that matter was composed of atoms and molecules and some of them were able to apply this knowledge to explain phase transitions of matter. In contrast, most elementary students did not know that matter was composed of particles such as atoms and molecules. Similarly, a study conducted by Ayas, Ozmen, & Calik, (2010) showed that tertiary level students had a better understanding of the particulate nature of matter than secondary level students.

Research results reported by Nakhleh et al. (2005) and Ayas et al. (2010) summarized above suggest that students’ understanding of the particulate nature of matter increase with educational level because students in higher grades demonstrated more knowledge about the particulate nature of matter than those in lower grades. However, Liu and Lesniak (2006) argued that the progression of students’ conceptions on matter from lower grades to high school is not automatic but it is multifaceted process, suggesting that there are other factors involved other than the level of education.

Research studies on pre-service teachers’ conceptions of the particulate nature of matter have provided evidence that teachers’ difficulties on this topic are similar to those displayed by middle and high school students. For example, Gabel et al. (1987) investigated prospective elementary teachers’ views about the particulate nature of matter using a test item, in which atoms and molecules of matter were drawn to represent the solid state. These teachers were asked to draw the particles after the solid had melted and became a liquid. The results revealed that many teachers did not conserve the number of particles, suggesting they displayed lack of knowledge about conservation of atoms or molecules. Another misconception Gabel et al. identified among the pre-service teachers was that the diagrams of the atoms got larger as matter changed from liquid to gas state, suggesting that the particles increased in size due to the physical change. In a similar study, Valanides (2000a) studied primary student teachers’ understanding of the particulate nature of matter and its transformations during dissolving. Valanides found that a majority of the student teachers exhibited perceptual rather than conceptual understanding of the particulate nature of matter and they had difficulties to relate the observable macroscopic changes to the invisible molecular events such as arrangement and movement of molecules. Haidar, (1997) investigated Yemen’s prospective teachers understanding of conservation of atoms and mass, the mole, atomic mass, and balancing chemical equations. The results showed that most prospective teachers depended on memorization of the concepts without meaningful understanding of the concepts. In a separate study, Valanides (2000b) investigated pre-service teachers’ understanding of the macroscopic and microscopic changes which would occur when different water solutions were distilled. The results showed that majority of the pre-service teachers exhibited limited understanding of the particulate nature of matter and the connection between the observable macroscopic changes and the way molecules in solutions and vapor moved in relation to one another and how they are held together. Valanides also reported that some pre-service teachers attributed the expansion of a liquid to the expansion of the molecules themselves and were unable to differentiate chemical from physical transformations.

Although several studies have been done on the particulate nature of matter, it is evident in the literature that most of these studies have mainly focused on teachers and students in Europe (Valanides, 2000a, 2000b), Asia (Haidar, 1997; Ozmen & Kenan, 2007, Tsai, 1999; Boz, 2006; Yilmaz & Alp, 2006; Ayas et al., 2010), and USA (Gabel, Samuel, & Hunn, 1987; Gabel, 1993). Very little is known about the African science teachers’ and students’ understanding of the particulate of nature of matter. For example, during our literature review we only located one study that examined South African secondary school pre-service science teachers’ and Nigerian high school students’ conceptions of nature of matter (Onwu & Randall, 2006). In recent times, Harrison and Treagust (2002) also recommended for more research at senior and post-secondary level that would inform practice. As such, there is need for more research on populations that little is known about their knowledge about the particulate nature of matter. In particular, no study has explored Zambian teachers’ and students’ understanding of the particulate nature of matter. Thus, such research has become necessary in the Zambian context. Therefore, the purpose of this study was to assess Zambian junior high school science pre-service teachers’ understanding of the particulate nature of matter. In particular, we assessed the pre-service science teachers’ knowledge about effect of phase change, cooling, heating and compression on the size of particles, spaces between particles, speed of particles, and number of particles in a substance.

In Zambia, science is a mandatory subject to all students from grades 1 (elementary school level) to 12 (high school level). From grades 1 to 9 students take general science subject that comprise of chemistry, earth science, biology and physics concepts and skills. The most common instructional mode in science classrooms is structured inquiry-based teaching where students are provided with detailed laboratory instructions but not the answer. The particulate nature of matter cuts across general science, chemistry, physics and biology subjects. The topic matter is first introduced elementary grades. The details on structure of matter are taught in middle and high schools. At high school level, the particulate nature of matter is dealt with in different chemistry and physics lessons. The concepts on structure of matter taught in school form a basis for learning other chemical and physics concepts at tertiary level of education. Therefore, pre-service science teachers’ sound understanding of the particulate nature of matter is important if they have to teach correct aspects of matter and other scientific concepts to their students.

This study is desirable, not only to Zambian science teacher educators but also to science educators elsewhere, who have a similar school science curriculum and teacher education program. It was also anticipated that the findings of this study would provide some implications for science teaching, learning and science curriculum design in teacher education where this study was conducted.