The purpose of this study is to devise the teaching method to develop the ability to distinguish whether we can investigate the problem. We call it "distinction of the problem". The teaching method has two features: (1) Letting them distinguish whether they can investigate the problem in a problem setting scene, (2) Letting them use the worksheet about the way of thinking to distinguish the problem. This teaching method was administered to the 64 sixth graders to investigate the availability of this new method. As a result of this research, the score of the post-test is significantly higher than the score of pre-test that measure the ability about "distinction of the problem". Therefore, the teaching method of this study is effective to development of this ability.