Critical think...

This study aims to obtain a valid and reliable formative evaluation model of critical thinking. The method used in this research was research and development by integrating Borg & Gall's model and Plomp's development model. The ten steps of Borg & Gall’s model were modified into five stages as the stages in the Plomp's model. The subjects in this study were 1,446 students of junior high schools in Yogyakarta Special Region or Daerah Istimewa Yogyakarta (DIY), 14 mathematics teachers, and six experts. The content validity employed was expert judgment, the empirical validity and reliability used were loading factor, item analysis using partial credit model (PCM) 1PL, and the relationship between disposition and critical thinking skill used was structural equation modeling (SEM). There are five aspects of critical thinking skill: mathematic reasoning, interpretation, analysis, evaluation, and inference, which entirely composed of 42 items. The validity of the critical thinking skill instruments achieves a significant degree as indicated by the lowest and highest loading factors of 0.38 and 0.74 subsequently, the reliability of every aspect in a good category. The average level of difficulty is 0.00 with the standard deviation of 0.45 which is in a good category. The peer assessment questionnaire of critica