In this study, we defined children’s competency as well as science teaching skills that should be developed as the ability to construct and express a science concept through collaborative problem solving. In order to develop children’s competency and skills, we designed a science lesson based on the proposal of Taylor et al. (1997). The lesson was a fourth grade science unit: “the volume of air changes when heated”. Results indicated that: (1) Children solved the problem collaboratively. (2) Children expressed their own ideas as performance. And they developed their ideas during the process of learning. (3) The teacher assessed the children’s thinking and provided feedback based on assessment. Our science lesson could foster the development of children’s competency and skills. The proposal of Taylor et al. (1997) was useful for designing the science lesson.