The present study deeply aims to reveal teachers' reflection and their reflective thinking levels on the different dimension of their teaching practice with regard to the dimension of learning objectives, content, learning-teaching process, and measurement and evaluation in the context of English courses. The study was designed as case study method. The study group was composed of 27 teachers selected based on the criterion sampling method. Results showed that the participant teachers had information about reflective thinking skills and they made some changes in the lesson plan because they thought that a lesson plan for the learning objectives ignoring students' prior knowledge was ineffective. Based on teachers' opinions, it was also determined that the content consisted of similar topics and was very intense and heavily based on vocabulary teaching. Results indicated that participant teachers reflected on teaching methods and techniques, activities and materials, student motivation, classroom atmosphere, and ensuring participation in the lesson. It was also revealed that the efficiency of measurement tools and the need to prepare measurement tools with regard to the learning objectives should be realized. Based on their reflective diaries, participant teachers also reflected at the technical, practical and critical levels and developed reflection-in-action, reflection-on-action, and reflection-for-action. Providing teachers with in-service training courses such as thinking skills, problem solving and decision making techniques, risk and crisis management that will contribute to overcoming their shortcoming and mistakes is thought to improve their reflective thinking skills.