The purpose of this study is to explore the epistemological foundation of science teachers' beliefs and understanding of students' activities in chemistry lessons. It also helps to find out the philosophical perspectives of science teachers and students to accomplish practical activities to transfer school science learning to activity-based instruction. Science teachers' teaching style, students' interaction and engagement in chemistry lessons and collaborative inquiry were closely observed and their epistemologies were documented and explored. Chemistry classes with practical activities were observed in two community schools located at Province 3 (Kathmandu), Nepal. Interpretive data were generated and analyzed concerning a philosophical perspective on play-way chemistry learning. The pragmatic methodological approach was applied, focusing on the experiences of students and their collaboration with the science teachers. The analysis of activity discourse showed that the learning and understanding of chemistry depend upon the basic epistemology of science teachers, activity-based learning and the collaboration between a science teacher and the students were conducted. The results suggest that the science teachers' dogmatic epistemology is the major hindrance and an influential factor resulting in students' poor understanding in chemistry lessons.