Systemicity which is a keynote of Mathematics means correlation of Mathematical content with concept
and hierarchical sequence. When systemicity is suggested for a hierarchical sequence in classroom
instruction, a teacher could make it clarify that which a concept or element in learning should be taught
first. And for students, it gives information for a more sophisticated concept and function in their learning.
Recently, Science or Computer subject which has systematic feature like Mathematic uses 'Knowledge Space
Theory' to analyze relation and hierarchy of a concept.
In this research paper, it is examined closely that 'Knowledge Space Theory' which is a part of
cognitive science for analyzing a hierarchy of concept and level of knowledge of users by using Group
Theory. Futhermore, we suggest an insight about classroom instruction of 'Knowledge Space Theory' using
a hierarchy of unit of area in the plane figure unit for Elementary school.