This study utilized multiple data sources to examine the beliefs about learning and teaching physics and the instructional practices of five beginning teachers and seven experienced teachers from Singapore. Our study was implemented in the unique context of teachers teaching the topic of electricity to students grouped according to academic abilities. The topic of electricity is one of the most difficult physics topics for students to understand and for teachers to teach. It was found that the experienced teachers, compared to the beginning teachers, tended to have beliefs about teaching and learning physics that are closer to constructivist views. The majority of the teachers, particularly the beginning teachers, espoused beliefs about learning physics that were incongruent with their beliefs about teaching physics. Although transmission-oriented and teacher-directed practices dominated the classroom lessons of both groups of teachers, more elements of constructivist instruction were found in the classroom lessons of the experienced teachers. It was also found that the classroom practices of the teachers, especially those in their inductive years of teaching, were more aligned with their beliefs about learning physics than their beliefs about teaching physics.