This study has identified the effectiveness of using portfolios for the prospective teachers as a tool of an explicit, reflective, and instructional approach in science education. Early childhood science method courses in a college for unskilled early childhood teachers influence their theory and practice toward science teaching. It describes these prospective teachers' beliefs of teaching science and their perspectives and views of nature of science have been changed. It explores how these changing conceptions, along with their teaching practice, developed during the procedure of the developing portfolios.