Japanese mathematics textbooks contain many worked-out examples. Japanese school teachers make frequent use of worked-out examples in mathematics class. However, they are not always using effectively in instruction. For example, some mathematics teachers have only intention of teaching students a set of procedures for solving problems. The purpose of this paper is to suggest more effective method of teaching students worked-out examples. The effective method has been studied from the point of view of subgoals and self-explanation. According to the experimentation of Catrambone (1994), learning subgoals enhanced performance because subgoals act as guides the procedure demonstrated in worked-out examples. Accoeding to the reseaches of Renkl (1997), successful learners tended to employ more principle-based explanation, more explication of operator-goal combinations, and more anticipative reasoning in their self-explanation. Worked-out exampls in Japanese mathematics textbooks don't express subgoals clearly. So, we suggest to express subgoals clearly in teaching worked-out examples. It is important that students understand the structure of solution through expressing subgoals clearly. When the teachers teach worked-out examples, I request them to employ more principle-based explanation, more explication of operator-goal combinations, and more anticipative reasoning. Students would be influenced by the teacher employed principle-based explanation, explication of operator-goal combinations, and anticipative reasoning.