Theoretical developments and key ideas that have been required in the new moral lesson established as a school subject are not new ones. Shuichi Katsuta sees a subjective behavior of judging values under one's responsibility as the fundamental part of morality. Katsuta also stressed that moral values were essentially in opposition and in contradiction. Akira Mori pointed out the relative nature of moral values. Those are the fundamental ideas of new moral lessons established as a school subject, such as a moral lesson by multifaceted and diverse ways of thinking, and a moral lesson by discussing. Moreover, the complementary relationship between the moral lesson and the subject lesson (Katsuta), and the unity of the inner self-awareness and the social practice of morality (Mori), those are also very suggestive when school teachers consider about moral lessons in future.

In order to correspond to the introduction of moral education into new national curriculum, firstly, the meaning and position of morality and the formation of value in citizenship education were examined from the viewpoint of teaching reform of morality on citizenship education in social studies. Secondly, the way of education on the relationship between morality and citizenship was compared and examined among the advanced three countries of the UK, Singapore and Hong Kong. As a result, following two points were clarified. 1) Currently in Japan, the argument did not extend to the stage aiming for the flourishing of humanity beyond citizenship like the UK. 2) From that point of view, the way of crossing citizenship education between civic education and value education like Singapore and Hong Kong will be effective for teaching morality in Japan.

(1) There are two phases in moral education; one is the stage in which valid norms in the society are accepted as the right, the other is the stage in which even valid norms in the society are doubted and discussed their rightness, and it is in the latter case that there needs discourse ethics which legitimates norms. Norms are separated into the moral and the value; the moral is given the legitimation, and the value connects to the specific and concrete way of life of groups and individuals, and the moral is given priority to. (2) Habermas' discourse ethics reconstructs the framework of modern education which is based on the concept of enlightenment. (3) Children who are the members of “the classroom as a society" reconstruct the norm system of the classroom by discussing and examining the legitimation of norms each other. During that process, constructive learning become possible when learner takes the hypothetical attitude to norms which seem valid in the existing society.