ABSTRACK
This research was carried out in January to March 2018 in SMA Negeri 1 Sragen which is located at Jalan Perintis Kemerdekaan No. 16 Sragen. The subject of this research was a teacher at SMA Negeri 1 Sragen. In this study, the researcher gained an in-depth understanding of the subject’s perspective using case study method. The sources of the data are informants, events, and documents. There were three techniques of data collection, namely interview, passive participant observation, and document analysis. The data were analysed using interactive model involving data reduction, data display, and drawing conclusion and verification.

There are some focused points related to teacher’s belief in critical thinking. First, the conception, is about the teacher’s conceptions about how she sees beliefs in critical thinking. Second, personal ideologies, is about her philosophy of how she wanted the teaching and learning process goes. Third, the values, is about the value of teaching critical thinking that needed to be shared to the students. The data findings also show her admitting that her beliefs are influenced by both internal and external factors. The internal factors consist of way of thinking, learning experience, teaching experience, and self-reflection. The external factors talk about her social relationship, curriculum, and the availability of resources. The impacts of her beliefs are shown in teaching approaches, materials selection, teaching activities, and her attitudes.

Overall, the data findings show that the teacher has a strong conception about her beliefs in critical thinking. The teacher has conducted critical thinking teaching practice. Teaching critical thinking is not just about sharing the understanding of thinking critically to the students but also beyond that. Teaching critical thinking is also making the students aware of the value and function of critical thinking in their life. Students can evaluate their thinking themselves because of the teaching and their self-reflection act.

Keywords: Teacher’s beliefs, critical thinking, teaching practice