Students' ideas on conservation of matter: Effects of expertise and context variables

Abstract

Recent research on chemistry learning and teaching has described some alternative conceptions held by students as to their understanding of the properties of matter. Several classifications have been proposed to analyze students' conceptions about matter and its changes. Starting from Anderson's categorization, this research studied students' understanding of the qualitative conservation of matter (substance), and how this understanding is influenced by previous instruction in chemistry and task variables. Here, task variables include chemical content and problem context. Four groups of adolescents that differed in age (from 12 to 17 years) and scientific instruction, and two groups of university students with different expertise in chemistry were presented with a 22‐item paper‐and‐pencil test about the conservation of matter. The items involved physical changes (solutions or changes of state) and chemical changes (reactions), and were posed both in academic chemistry contexts and everyday situations. Results show the influence of group membership, task content, and problem context on students' performance. Test scores increased with age and instruction in chemistry, but the influence of chemical expertise was smaller than that predicted from research in other scientific areas. Concerning context, for everyday situations reactions are the most difficult content; on the other hand, in academic chemistry the most difficult content was solutions. Analyses for category answers showed that subjects are likely to concentrate their interpretations in two main categories, interaction (substances interact to form new ones) and modification with identity (substances modified in appearance continue to be the same). However, conceptions depend also significantly on content and context task. Finally, we have found that science instruction increases the consistency of the conceptions held by subjects. Younger subjects and adolescents without scientific instruction tended to be less consistent than more expert subjects. © 1995 John Wiley & Sons, Inc.

Seventh-grade Students' Understanding of Chemical Reactions: Reflections from an Action Research Interview Study

“…In most cases, the first particle model to be introduced in chemistry teaching is a model of discrete particles. Hesse and Anderson (1992) outlined that an understanding of chemical reactions must be introduced as a change in the constituent discrete particles of the initial substances (Andersson, 1986;Gomez, Pozo & Sanz, 1995). This strategy promises to foster better understanding of the distinctions between chemical reactions and physical changes.…”

“…Thus, some students may think that matter exists without having any mass and, consequently, that chemical changes result in the loss of mass or in the creation of something from nothing (Stavy, 1990). Gomez et al (1995) stated that the principle of the conservation of mass is more frequently accepted for physical changes rather than for chemical reactions. These problems are not restricted to early chemistry learning, but they often occur among older students who have been taught chemistry for many years (Valanides et al, 2003).…”

Investigating Student Understanding of the Law of Conservation of Matter

“…Later studies created additional support for the findings that students acquire conservation skills gradually (Agung & Schwartz, 2007;Gomez et al 1995;Gulko et al 2001;Haidar, 1997;Ozmen & Ayas, 2003). Gulko et al (2001) studied developmental patterns in conservation skills in 390 children, aged 4-11 using the Goldschmid and Bentler Concept Assessment Kit.…”

“…Very recent research that points to a deficit in student understanding of chemical reactions is not surprising since many researchers have come to the conclusion that conservation of matter is a difficult concept to learn (Agung & Schwartz, 2007;Gomez, Pozo, & Sanz, 1995;Gulko, Doyle, Serbin, & White, 2001;Piaget & Inhelder, 1974;Stavy, 1990). Students learn conservation of matter gradually.…”

Misconceptions among Middle School Students Regarding the Conservation of Mass during Combustion

“…Students' answers are intuitive (Melamed, 2000) and/or naïve (Pundak, Rosner, & Maharshak, 2005), and reflect a misrepresentation of scientific conceptions. One possible reason for this is that students may find it difficult to distinguish the macroscopic from the microscopic world, and therefore, do not understand chemical reactions and the conservation of mass (Sanz, 2006).…”