Students' understanding of the particulate nature of matter

School Science and Mathematics, Jan 2003 by Singer, Jonathan E, Wu, Hsin-Kai, Tal, Revital

The particulate nature of matter is identified in science education standards as one of the fundamental concepts that students should understand at the middle school level. However, science education research in indicates that secondary school students have difficulties understanding the structure of matter. The purpose of the study is to describe how engaging in an extended projectbased unit developed urban middle school students' understanding of the particulate nature of matter. Multiple sources of data were collected, including pre- and posttests, interviews, students' drawings, and video recordings of classroom activities. One teacher and her five classes were chosen for an indepth study. Analyses of data show that after experiencing a series of learning activities the majority of students acquired substantial content knowledge. Additionally, the finding indicates that students' understanding of the particulate nature of matter improved over time and that they retained and even reinforced their understanding after applying the concept. Discussions of the design features of curriculum and the teacher's use of multiple representations might provide insights into the effectiveness of learning activities in the unit.

The particulate nature of matter is identified in science education standards as one ofthe fundamental concepts that students should understand at the middle school level (American Association for the Advancement of Science [AAAS], 1993). However, empirical studies in science education indicate that secondary school students have difficulty understanding the structure of matter (Ben-Zvi, Eylon, & Silberstein, 1986; Krajcik, 1991) and hold several alternative conceptions of atoms and molecules (Griffiths & Preston, 1992). For example, some students maintain a cloud or vapor model of air (Krajcik, 1989), attribute the properties of substances to an isolated atom (Ben-Zvi et al., 1986), and believe that a molecule changes its size and shape at different temperatures (Griffiths & Preston, 1992). Additional studies show that students have difficulty relating macroscopic properties to the movement and arrangement of particles, even after engaging in substantial chemistry instruction (Ben-Zvi, Eylon, & Silberstein, 1987; O'Connor, 1997). The purpose of this study is to describe how urban middle school students' understanding of the particulate nature of matter is developed by engaging in an extended project-based unit.

The reported research is part of a large-scale urban reform effort involving collaboration between a large midwestern urban center and a large midwestern university. In order to facilitate students' understanding of particulate nature of matter, our research group developed a 9-week curriculum entitled, "What Affects the Quality of Air in My Community?" (referred to in this article as "air quality unit"). The intent of this unit was to provide a range of learning opportunities for students to explore their prior ideas, communicate their ideas through the use of multiple representations, and investigate concepts of atoms and molecules. The curriculum materials address science content associated with the particulate nature of matter, phase changes, and the chemical processes involved in the formation of pollutants. To examine how the curriculum engages students in constructing understanding ofthe particulate nature of matter, this study is guided by the following question: How do proj ect-based classroom experiences and materials shape and promote urban students' understanding of the particulate nature of matter? Findings of the study will extend educators' understandings of curriculum design and students' learning of the fundamental scientific concepts.

Project-Based Science

Fundamental characteristics of project based science (PBS) include providing a context that engages students in extended authentic investigations through using a driving question, promoting collaboration, using cognitive tools, and communicating their ideas (Singer, Marx, Krajcik & Chambers, 2000; Krajcik, Blumenfeld, Marx, & Soloway, 1994; Marx, Blumenfeld, Krajcik, & Soloway, 1997). The purpose ofthe driving question is to link concepts and principles and drive activities and investigations. The question may be teacher or student generated and must provide sufficient creative latitude for multiple avenues of problem solving (Krajcik, Czerniak, & Berger, 1999). Projects are designed to foster student collaboration within a learning community. Students communicate with each other, teachers, community members, and scientists to find information and solutions to their questions and to discuss their findings and understandings. Projects are designed to extend student learning experiences beyond the classroom by posing driving questions that situate the science with issues that are likely to be of interest to scientists, community-based organizations, and families. Collaboration during investigations and lessons involve students interacting with peers in small groups or as part of large class discussions, or students are given opportunities to interact with more knowledgeable community members.