In Hong Kong, the educational reform launched by the Education Bureau since year 2000 encouraged primary schools to use the inquiry approach in the teaching of science and technology related topics in General Studies. It is believed that this approach is a student-centred approach which helps students to integrate generic skills, knowledge and values in the learning of General Studies. However, primary school teachers in Hong Kong do not commonly practice the inquiry approach in the teaching of General Studies because they found this approach time consuming and difficult to manage with the limited time of each lesson. Students hence have few opportunities of trying out experiments and science concepts are usually learned by rote without real understanding. This paper illustrates how a group of teachers in a primary school, collaborated with the researchers from The Hong Kong Institute of Education, used the Learning Study approach in planning and teaching a Primary 4 General Studies topic about "Light and shadow". During the study, the team found that one of the problems of students was that they were only able to repeat the statement "Light travels in a straight line" but could not apply the concept to explain daily life phenomena, such as the formation of a shadow. In this study, the research team identified an important object of learning which was omitted in the textbook. In the lessons, the inquiry approach was used, which provided opportunities for students to investigate the concept of "Light travels in a straight line". By improving the design and the enactment of the Variation pattern in different teaching cycles, a more effective lesson design was achieved, resulting in better student learning outcomes as shown by the pre and post student interviews and test results of the Learning Study.