This research aimed to improve the quality of students in Srikranuanwittayakom School using the concept of "Teach Less, Learn More." The method used in this study was Participatory Action Research, and there were twenty teachers voluntarily participating. The study had been done in two semesters of the academic year 2020. The three expectations from the development outcomes were: (1) the improvement under the identified indicators: a) teacher performance, b) organizing teaching activities and c) the students characteristic, (2) the researcher, the research participants, and the entire teaching staff learned from practice, and (3) the body of knowledge, which had been obtained from the practice as a foundation theory in this school context. The results of the study revealed three key features. Firstly, the average means of teacher performance, organization of teaching activities, and student characteristics after the 1st and after the 2nd cycles were higher than before the operation. Secondly, after adopting a participatory approach, researchers, co-researchers, and the entire teaching staff learned the importance and benefits of team collaboration. Lastly, the knowledge gained from the practice of this research consists of the ideas and strategies of the following concepts: 1) Expected change, 2) Driving factors for change, 3) Resistance to change and 4) Overcoming resistance drive change. The details of each issue can be used as a model for the students' quality development according to the concept of "Teach Less, Learn More" continuously. Moreover, the concept can be applied to other new conceptual developments.