Research in science education supports that science teaching and learning must be developed as a process of (re)construction of knowledge based on scientific practices. In that sense, learning is conceived as a process of evolution and conceptual and epistemological change, and hence, science teaching has to be planned as the implementation of a plan of activities to promote this change. But, to what extent is it possible to organize science teaching, especially Physics and Chemistry, with a problematized structure? Does it produce an improvement in students' attitudes towards science learning? Could this methodology generate rejection amongst students given that it is more demanding than the usual methodology? In this work we present a protocol for planning science teaching with a problematized structure. We also report some results on attitudes from secondary education students that were instructed according to this methodology. Data on students’ attitudes were obtained from an experimental group of a total of 784 students from seven different teachers, and we compare these data with that from a control group of 635 students from nine different teachers. Results show the positive effects of organizing Physics and Chemistry teaching with a problematized structure, as students from the experimental group acquired positive expectations that were significantly higher than those from students of the control group.