Research has shown that interest and engagement in learning physics declines with years of schooling, and leads to low enrolment later on in physics courses. Since the first experiences with physics in elementary education is important for the formation of attitudes and interest in physics, the aim of this research was to examine the contextual and individual determinants of engagement in physics from the elementary school physics teachers' perspective. The contextual model of student engagement was used as a conceptual framework. Twelve in-depth semi-structured interviews were conducted with physics teachers (nine females). A phenomenological approach was used. The research findings show that, in addition to motivational beliefs, students' personality characteristics also had an important role for interactions with the teacher and for the completion of class activities. Regarding the contextual determinants of student engagement, teachers described their role and the role of parents and peers. The role of the teacher is twofold and is reflected through positive relationships with students (social relatedness contexts) and teaching methods (instructional context). Teachers' responses suggest that student engagement stems from the complex interaction of individual and contextual determinants that successful teachers direct in order for their students to achieve the best possible educational outcomes.