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We investigated the effect of the context-based approach on 9 th grade students' conceptions of the Periodic Table . Within a nonequivalent pretest-posttest control group design the study was conducted with 80 grade 9 students (aged 15-16) drawn from two classes (39 and 41 students) in a high school in Turkey. The experimental group was exposed to the context-based material, while the control group was taught with the traditional approach (teacher's explanation, question and answer, writing, etc.). The results of this study indicated that the use of storylines embedded within the context-based learning resulted in the students in the experimental group performing better with respect to understanding concepts of the Periodic Table and gaining more positive attitudes towards chemistry than did those in the control group, and this improved performance was also observed in a test taken ten weeks after the treatment. Some suggestions are made on implications for practice and learning.

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The research reported here consists of the introduction of an intervention based on a series of laboratory activities combined with concept mapping. The purpose of this intervention was to enhance student understanding of acid-base chemistry for tenth grade students_ from two classes in a Turkish high school. An additional aim was to enhance student attitude toward chemistry. In the research design, two cohorts of students were compared; those from the intervention group (N=31) and a second group (N=28) who were taught in a more traditional manner. Student understanding of acidbase chemistry was evaluated with a pretest/posttest research design using a purposedesigned instrument, the Concept Achievement Test (CAT) consisting of 25 items, 15 multiple choice and ten multiple choice with explanation. Alternative conceptions identified in the pretest were incorporated into the intervention, which thereby sought to move students toward views more in accord with scientific views for the concepts. Statistical tests indicate the instrument is reliable (with an alpha reliability of 0.81) and the analysis of the findings revealed statistically significant differences between the intervention and traditional groups with respect to conceptual understanding. Examination of student explanations and analyses of semi-structured interviews conducted with selected students suggest that the main influence was the laboratory activities. Analysis of the findings in the context of relevant literature that concept mapping in conjunction with laboratory activities is more enjoyable, helps student link concepts, and reduces their alternative conceptions.

Öz