By doing all of the research stages which are: 1) formulation of the theory in the form of the
initial (draft level critical thinking) based on the study of theory supported by empirical data, 2)
validate the draft level critical thinking to experts to determine the validity of the construct and
empirically according to the theory developed, 3) pre-research to prove the existence of levels of
thinking critically revised the draft level critical thinking based on the results of pre-research, 4) data
collection to determine the existence of level critical thinking skills in mathematics according to the
hypothetical theory is made, 5) the method of comparative analysis to determine the reliability
hierarchy, we generated critical thinking skills that are formulated (LCTA- 0 until LCTA-3).