An analysis of the terminological structure of index terms in textbooks

The purpose of this study is to reveal the characteristics of the terminological structure formed by the index terms of junior-high school, high school and university-level textbooks. We first identify the types of concept of index terms, and then uncover the conceptual structure that underlies index terms. We found that, as the school level progresses, (1) the balance of concept types of index terms shift from concrete objects to their behaviours or features, (2) index terms as a whole shifts from a set of fragmented terms to a single indirectly-related group, (3) the core part of the index terms comes to be occupied by terms which represent concepts other than concrete objects.