Learning Study has been employed in pre-service teacher training in Hong Kong since 2007. This presentation by pre-service teachers introduces their use of Variation Theory in and learning from three Learning Study projects in Hong Kong.Project 1 focuses on the teaching map reading skills for understanding Hong Kong landscapes in General Studies of primary four. Two lessons were designed and taught collaboratively by a group of six preservice teachers in 2016. In order to reach the object of learning, i.e., the ability of reading a map, four critical features were confirmed according to the pre-test: the names of the three map symbols (CF1), the functions of the map symbols (CF2), the names of the eight directions in Chinese (CF3) and understanding the questions about directions (CF4). Throughout the two lessons, Variation Theory was the main method to highlight the critical features for students. The pedagogical design of Lesson 2 was revised after the postlesson reflection based on the post- test and observation of Lesson 1. It was confirmed by the pre- test and post- test results that, improvement of students’ability in map reading was bigger in Lesson 2 than Lesson 1.Project 2 focuses on teaching the use of adjectives to primary two students. After a pre-test was conducted, the critical features identified were 1) function of nouns, 2) function of adjectives, 3) the positioning of adjectives and 4) the practical application of adjectives. A total of two lessons were deliberately designed and co-taught by a team of pre-service teachers. It was found that Lesson 2 achieved better improvement in the post-test than in the pre-test, compared to Lesson 1. The key factors producing such differences included blackboard management, activity formats and reiteration of concepts. The results suggest the need to consolidate variation theory and its relevant facilitating factors in order to achieve the most suitable pedagogical design wherein students learn the object of learning