In this paper I started with a question that the piano teaching methods at the department of education have too much focus on the specialist curriculum, which is often seen at music colleges or conservatories. Contrary to those methods for a specialist curriculum, I devised a new method to train students' ability in music which would be applicable for different situations in school, for example string or blass ensemble, chorus, etc. This method was put in practice in group lesson form. I used many pieces for four hands as well as solo music in various styles and characters as materials. This paper reports a practical study under the concept of how to grasp various music theories and knowledge and how to develop them into the live musical expression, using piano as the medium.