Inquiry-based science education (IBSE) has become a prominent approach in science educational reform in all countries. This research is a case study to analyse the practices of IBSE in the science class of one Junior High School in Chiang Rai, Thailand, as part of the overseas teaching practicum project conducted by SEAMEO. Respondents were two Filipino teachers of the English Programme Class, and have worked for three years. Adaptation of IBSE in the curriculum was captured by analysing the Thai's science curriculum. The concepts of IBSE were analysed in the teachers' syllabus and lesson plans. A series of classroom observation was also done to check the real practices of IBSE, while all activities were noted and recorded. Additional information on teachers' perspectives on IBSE had been obtained through structured interviews. Analysis was based on the Tafoya's concept of inquiry levels to examine the type of inquiry. The research confirmed that the concept of IBSE has been written in the lower secondary science curriculum in Thailand. Both teachers have shown relatively good perspectives on science and IBSE, and commonly applied the structured inquiry, in which teachers still dominate the learning process, but students have also been involved.