In the Philippines, the recent implementation of the K to 12 curriculum for the basic education has impelled the attention of policy makers, educators and researchers for teachers’ professional development. In this study, with the primary purpose of re-aligning teachers’ knowledge to the goals of the new curriculum, university science education experts established a collaborative professional community with 30 elementary school science teachers with the aim to investigate and co-construct their understanding about science teaching and learning. Collaboration was a year-long activity which started with training where teachers are exposed to collaborative lesson planning and used the lesson plan as their object of learning. The year-long professional development activity includes goal setting, lesson implementation and observation, critiquing and reflection, and revision of the lesson plan, and re-implementation of the revised lesson plan. As a results teacher assessed the activity as a sustainable effort which enhanced many facets of their teaching careers which include their cognitive views on science teaching, reflection and shared accountability. University experts also noted that the gains in the improvement of teachers’ instructional practices were dependent on their mutual and constant collegial and constructive interactions.