Analyzing of the errors in mathematic lessons by secondary education students

In this research, it is aimed to identify types of error made by secondary education students in the mathematics field and determine the observation frequency of errors related to age of students (class level). Within the frame of this aim we examined the answers of the questions as; ?what kind of errors are observed, the frequency of observed errors, how these types of errors and the frequency of them changes according to students age (class size. In this research, we used the phenomenology which is one of the qualitative research methods and we gathered the data using by 480 (4x120) mathematics exam papers of 9, 10, 11 and 12. grades in both semesters of 2012-2013 academic year. Data were analyzed through the document analysis method and besides benefited from non-structured observation and interviews in order to support the research findings of the analysis. Error types are categorized into these 5 headings in the light of gathered data and literature as originated from methods of doing mathematics, representation, demonstration and symbolization, solution method and strategies algebraic operations we also examined the frequencies of these error types related to class level. The finding of this research shows that the error types are different with respect to class level of students. We though that the reason of this differentiation derived from the structures of error types, level of students and feed backs given to this errors. Because of there is not enough study in identifying error types and frequencies it is though that this research could make a major contribution to mathematics teaching. In the light of results of the research some suggestions are made to teachers and researchers.