Some academic societies for education were interested in and studied the education of developments of solids. We can find their various contributions to the usual education of developments that is conducted with handicraft tools such as papers, scissors and pastes. On the other hand, computer environments in elementary schools are getting better, and therefore, the use of an electronic tool in the education of developments of solids can be regarded as an important means that leads to higher educational effect. A few electronic tools were developed, but an effect of class using such an electronic tool was not verified in terms of academic ability. We developed another electronic tool “TENKAI” for learning developments of a cube and a rectangular parallelepiped. To verify an effect of class using TENKAI in terms of academic ability, we set a control group and an experimental group, and conducted experimental classes on developments. The experimental classes were conducted with a normal method for the control group; and conducted with TENKAI for the experimental group. Consequently, the academic ability in the experimental group tended to be higher than that in the control group.
