An investigation of secondary school seventh-grade students' classification behaviors related to the concepts of physical and chemical change

The aim of this study is to examine seventh-grade students' classification behaviours related to the concepts of physical and chemical change and to investigate whether these classification behaviours differ in terms of academic achievement level in the science course and gender. This study was conducted at the end of the fall semester of the 2017-2018 education year and involved 213 seventh-grade students from 5 secondary schools located in Seyhan and Çukurova districts of Adana. Data were collected through the Physical and Chemical Change Concept Classification Test (PCCCCT) that was developed by the researcher and consisted of 24 multiple-choice questions. In the first phase of the two-phase test, the participants were asked to classify the examples given as physical and chemical changes. In the second phase, they were asked to select the explanations which indicated why the examples given belonged to the concept. Data were analysed descriptively through frequencies, percentages, arithmetic means, and standard deviation by using the total scores of the classification of the physical and chemical change concept examples according to the concept name and the total scores obtained from the explanations used in the classification t-test and one-way ANOVA tests were used when the scores showed normal distribution in order to determine whether the total scores obtained from PCCCCT, the total scores obtained from the classification according to the concept name, and the total scores obtained from the explanations used in the classification differed in terms of gender and academic achievement level in the science course. Kruskal Wallis H-test and Mann Whitney U-test were used when the total scores did not show normal distribution. The results showed that the classification scores according to the concept name were below mean for the 52% of the examples that belonged to physical change and 44% of the examples that belonged to chemical change. Similarly, the scores for the correct identification of the justifications used for the classification were below mean in 60% of the participants for the physical change examples and in 54% of the participants for the chemical change examples. An assessment of the scores for the classification scores of the examples of physical and chemical change examples when the name of the concept was given and the explanation scores used for classification showed that the seventh-grade students could classify and explain the examples of the chemical change concept more accurately than the examples of the physical change concept. In a similar vein, the students were found to classify the examples of the physical change concept more inaccurately in comparison to the examples of the chemical change concept. On the other hand, the results also showed that the participants classified the new examples of the concept of physical change more accurately in comparison to the examples encountered before. The results of the study indicated that the total scores obtained from PCCCCT, the total scores obtained from the classification according to the concept name, and the total scores obtained from the explanations used in the classification displayed a significant difference in favour of the female students. Similarly, the total scores obtained from PCCCCT, the total scores obtained from the classification according to the concept name, and the total scores obtained from the explanations used in the classification displayed a significant difference in terms of the academic achievement in the science course in favour of the students who had high academic achievement levels. The results of the study showed that the success in the classification of the physical and chemical change concepts, fundamental concepts of the science course, was below mean, and the scores obtained from the examples used for classification were lower. Therefore, instruction of the concept examples should involve not only the examples but also the explanation of the critical attributes of the concept. The instruction of the examples should also involve comparisons with non-examples as well as explanations with reasons. Keywords: Physical change, chemical change, classification behaviour, over-generalization, under-generalization.