ANALYSIS OF STUDENT ERRORS IN SOLVING PROBLEMS OF ALGEBRA OPERATIONS IN CLASS VIII MEDAN JUNIOR HIGH SCHOOL ACADEMIC YEAR 2012/2013

The purposes of this research is (1) Knowing kinds of students errors in solve problems of algebra operations in class VIII(2) Knowing the level of students errors in solve problems of algebra operation in class VIII (3) Knowing the factors that causes students errors in solve problems of algebra operations in class VIII. Population in this research was Medan Junior High School and the sample was Class VIIID SMP Shafiyyatul Amaliyah,Class VIIIA SMP Budi Satrya and Class VIIIC SMP Negeri 14 Medan taken of the data of Ministry Education in Medan. All of subject in that 3 school is 98 students. Data collected by test, interview and observation. Test used for knowing kinds of error and level error by student, interview used for knowing the factors of students error when answer the question and observation for knowing the factors of students errors from teacher. Analysis method used is qualitative and quantitave description.The result of research showed that : (1) kinds of errors which many done by students were transformation error, skill process error and encoding error. (2) The level of students error in solving problems of algebra operation in class VIII Medan junior high school could be concluded that still very high error. (3) The factors that causes students error in solving problems of algebra operation divided into 2 factors: a. Internal factors (Lack of master concept,principle and skill in algebra operation, Lack of master prerequisites material, Lack of exercise solving mathematics problems, Students were careless) and b. External factors(Teacher was not as good demonstrator, Teacher was not good controller class, and Teacher was not good mediator).