This paper attempts to clarify the meaning of ‘knowing that’ and its implications in the context of education, focusing on the evidence condition of knowledge. Even though ‘knowing that’ is logically distinct from ‘knowing how to do’, there is some connection between the two, The ability of suggesting adequate evidence to the challenging question, such as ‘How do you know?’, is one of the logically necessary conditions of ‘knowing that’, referred to as the ‘evidence condition’, This ability may be regarded as a kind of ‘knowing how to do,’ since ‘knowing how to do’ covers both theoretical and practical domains. We teach knowledge to pupils so that they become capable of thinking by way of modes of knowledge they have been taught, they learn to think historically, for example. Thinking historically consists of knowing how to use historical facts, as well as knowing about historical facts. Therefore, thinking historically involves two kinds of ability, one to apply already-known facts to theoretical or practical situation, and the other to support historical facts by giving adequate explanation. To give adequate explanation presupposes, to some extent, awareness of the logical characteristics of modes of knowledge. From the educational point of view, ‘knowing that’ in pupils is said to grow in three senses. In the quantitative sense, pupils learn to know propositions which they didn’t know; in the qualitative sense, they learn to know a certain proposition more deeply by acquiring more adequate evidence than before, and in the potential sense, pupils are more inclined to examine their knowledge critically against experience, because of the realization of their ignorance in the course of knowing. It is important to distinguish the two cases in which ‘knowing that’ without evidence condition is said to occur. ‘Knowing that’ which cannot have evidence condition such as ‘knowing that 2+2=4’ ‘knowing that the sky is blue’, This kind of ‘knowing that’ serves as the basis of assessing the truth or falsehood of other propositions which fall to the same modes of knowledge. The other is ‘knowing that’ which lacks adequate evidence when the knowledge can and should he supported by evidence. Of course, this kind of ‘knowing that is incomplete from the philosophical point of view, but it may be worth considering in the educational context, This kind of ‘knowing that’ is inevitable to a certain extent, partly due to the limitations of pupils’ intellectual ability and partly due to the pressure of social convention.