In historical learning, to grasp the causal relationship between historical events and to understand factors that bring about important events are significant for fostering the historical thinking. However, some students are not able to find historical events that have causal relationships. The view of observing the historical events is different among individuals, so it is not appropriate to define the historical events that have causal relationships and impose students to remember them. The students need to understand the definition of the causal relationships and find the historical events that satisfy the definition according to their viewpoints. The objective of this paper is to develop a support system for understanding the meaning of a causal relationship and creating causal relation graphs that represent the causal relationships between historical events. When historical events have a causal relationship, a state change caused by one event becomes the cause of the other event. To consider these state changes is critically important to connect historical events. This paper proposes steps for considering causal relationships between historical events by arranging the state changes of historical people along with them. It also develops the system that supports students to create the causal relation graph according to the state changes. In our system, firstly, the interface for arranging state changes of historical people according to the historical events is given. Then, the interface for drawing the causal relation graph of historical events is provided in which state changes are automatically indicated on the created links in the causal relation graph. By observing the indicated state changes on the links, students are able to check by themselves whether their causal relation graphs correctly represent the causal relationships between historical events.

We conducted experimental classes in an elementary school to examine how the advantages of using stereoscopic 3D images could be applied in education. More specifically, we selected a unit of the Tumulus period in Japan for sixth-graders as the source of our 3D educational materials. This unit represents part of the coursework for the topic of Japanese history. The educational materials used in our study included stereoscopic 3D images for examining the stone chambers and Haniwa (i.e., terracotta clay figures) of the Tumulus period. The results of our experimental class showed that 3D educational materials helped students focus on specific parts in images such as attached objects of the Haniwa and also understand 3D spaces and concavo-convex shapes. The experimental class revealed that 3D educational materials also helped students come up with novel questions regarding attached objects of the Haniwa, and Haniwa's spatial balance and spatial alignment. The results suggest that the educational use of stereoscopic 3D images is worthwhile in that they lead to question and hypothesis generation and an inquiry-based learning approach to history.