The purpose of this study is to show the validity of introducing the "scientific terminology" in classroom teaching at elementary school for understanding of scientific contents by a learner. In particular, for the unit of fifth-grade science "functions of running water", we introduce the "scientific terminology" of "erosion", "transportation", "deposition" in the process of classroom teaching, and analyze and consider the learners' work & record books to elucidate the process of understanding of the current contents, we deduce the following results; (1) When students come to learn new materials, they utilize the acquired scientific terminology. (2) They can also explain natural phenomena observed around them by making use of scientific terminology they learned. (3) They can acquire the proper scientific knowledge regarding the "functions of running water". Therefore, we could show the validity of introducing "scientific terminology" for the understanding of scientific contents in elementary classroom.