SUMMARY
This study aims to develop inquiry-based teaching model that can enhance students' critical thinking abilities. The teaching model was developed through four stages, namely: (1) Preliminary Investigation, (2) Design, (3) Realization, and (4) Test, Evaluation and Revision. Teaching model developed consisted of five components, namely: (1) the model purpose, (2) syntax, (3) reaction principle, (4) social system, and (5) support system. The model purpose was to enhance the critical thinking abilities. Syntax of inquiry-based teaching model consisted of six phases, namely: (1) Confronting problem, (2) Asking conjecture, (3) Collecting Data, (4) Formulating explanation, (5) Explaining conclusion, and (6) Conducting Reflection. The principle of reaction was to provide technical assistance, ask for a review, and provide feedback. The social system emphasized cooperative learning, the medium social structure, and discussion. Support system included learning instruments as well as the tools and materials supporting the model. Development of teaching model was expected to meet the criteria of validity, practicality, and effectiveness. The study also developed research instruments in accordance with the purpose of research. The results of expert assessment showed that the teaching model developed meet the criteria of validity with a value of 3.22 and can be implemented in the field. Field test did twice in SMP Negeri 2 Bojonegoro in a different class because an enhance students' critical thinking abilities at first test less significant, although the model was already practical. The result of teaching model realization was 3.12 so it can be said that the teaching model meets the criteria of practicality. The result of t-test analysis of the students' critical thinking abilities showed a p-value of 0.028. This meant that there has been an increase in students' critical thinking abilities significantly. The response of students to teaching model was positively associated with the percentage of 73.77%. Result of the assessment of student activity during the learning of 3.07 was included in the active category. Based on these things can be said that the inqu