This research is qualitative descriptive with the aim to know the student’s lateral thinking process in solving open
problems (open ended problems). The research’s located in SMP Plus Darus Sholah Jember. The subject of research are three
students in VIII-F grade who have high, medium, and low capability in solving open ended problem. Data collection method used
are test, interview, and questionnaire. The data collection have done by giving three open ended problems that related with
rectangular and square material to be solved by VIII-F grade students. The result of this rsearch showed that the lateral thinking
process of three students in solving prolems (open ended problems) have been various.