In the elementary school mathematics curriculum, the number line is used mainly as an
iconic representation in the number area and its operations. The activities using the number line
can be replaced by the display of an educational tool, as well as illustrate the operation of the
process to be utilized in various ways. The number line symbolizes the active representation
of the type represented by mathematical abstraction; and, in the process, the ‘number of
operations' area, the 'shape' area, and the 'measure' area with a link that connects them
through the process. According to the 2007 Revised Mathematics Curriculum in the elementary
mathematics textbooks, the number line can show time, capacity, weight, and the range of
numbers in the 'measure' area. This study investigates the content of these sections of the
curriculum as it is covered in textbooks, and teacher's instructions regarding the number line.
In addition, the usage of the number line in the United States and Japan - that is, as it is used
in the measure area in the elementary mathematics textbooks - is examined with respect to how
it is taught and its implications for utilization. According to the analyses of this study, and the
Korean elementary mathematics curriculum, the marked number line which is presented in our
textbooks is used simply to count the visible grid; it cannot lead to a deeper understanding of
the use of the number line. An empty number line or mental number lines are required. The
number line is an important visual representation of mathematical concepts in the elementary
mathematics. Moreover, the ‘number and operations’ and the ‘measurement’ areas are
associated with a cross-realm connection through the number line. Its applications and the
relationships between elementary and middle school grades in mathematics will be discussed
in the later studies.