Number pair is a concept that represents position. The former number represents a column and the latter number represents a row. For example, (2,5) means that its position is the second column and the fifth row. Pairs of vertical rows are called columns and horizontal rows are called rows. Determine which column is generally counted from left to right and which row is generally counted from front to back. Example: Line 5, Line 4, Line 3, Line 2, Line 1 Line, Line 123456, Column, Column, Column, Black Dot in Column 4, Line 3, can be expressed as (4,3) by a number pair. Number pairs can describe the position of an object on a plane, which has the same function as coordinates in a coordinate system, and are both positioning. But it cannot be called a coordinate system. A coordinate system should have three elements, namely coordinate origin, unit length and direction. If (0,0) is defined as the coordinate origin, the number pair has the same function as the coordinate system. Plane rectangular coordinate system is also called Cartesian coordinate system. Don't talk about the concept of rectangular coordinate system when learning math pairs in primary schools. The intention of textbook design is to explain that the concept of mathematics comes from life through the idea of infiltrating coordinates by numbers.