Learning Study, in the form of an action research, has been proved to be an effective platform for school-based teacher professional development in Hong Kong. It is grounded in the Variation Theory developed by Ference Marton. In each Learning Study, teachers of a certain subject in a school work collaboratively with staffs from the Hong Kong Institute of Education to plan and teach a lesson targeting to achieve some important goals and/or to solve some learning difficulties in the curriculum of that subject. This presentation is about a Learning Study of a junior secondary school science topic "Eyes and Vision". In this Learning Study, drawing of ray diagram was identified to be a critical learning difficulty of the students. Activities were then designed based on the Variation Theory. Students were expected to develop the ability to use ray diagrams to describe, explain and predict phenomena about seeing sharp and blurred images through these activities. They could investigate light propagation and the formation of image through one phenomenon without involving advanced knowledge in either reflection or refraction. The whole process of conducting the Learning Study will be reported. It includes the identification of learning difficulties, the planning and the teaching of the lesson and the evaluation of the learning outcomes.
