Öz The study aimed at making evident the process of change in the beliefs of a science teacher resulting from classroom practices. The process of change was addressed by finding the beliefs held in comparison to other teachers, compatibility of held beliefs with constructivist principles of learning and changes observed during the two years. The data were collected through science teacher belief questionnaire, video recordings and teacher interview. Some encouraging evidence was in favor of practice changing beliefs about student involvement in lessons were found. The teacher started valuing students’ agreement on outcomes of the learning and spent more time in listening to the students rather than instructing them. The sequence in which changes were observed has great potential for facilitating the Continuous Professional Development (CPD) of teachers