A case study on concept definitions and images of ninth grade students about the concept of function

The aim of this research is to determine the concept definitions and images of ninth grade students about the concept of function and to make assessment. Participants consist of 10 students attending ninth grade in a secondary educational intuition in 2010-2011 educational year. 8 of the students are female, and 2 are male. Students chosen for interview are chosen according to aimed sample technique (Patton,1990) and participated voluntarily. Data are obtained from interviews, written documents of students (practical exams, exams) and classroom observations. In analysis, to define the concept images they have according to their answers, interview questions are especially focused. All of the data obtained are analyzed by concept image and concept definition structure developed by Tall and Vinner (1981)These explanations can be made in the light of data collected and analysis:Concept images of ninth grade students about the concept of function they have learned as a new concept are quite weak. This can be conducted from the interviews. Most students cannot step out of the definitions and examples set by teacher. And most students cannot go beyond drawing sets to define function.Another finding of this research is that, concept images of teacher and students about function definition affect each other directly. Student establishes a concept image within the concept image of the teacher.In the research, within the findings, suggestions are made for researchers and educators who wish to study about these issues.