First, draw two vertical lines on the notebook with a ruler. The horizontal line is the X-axis and the vertical line is the Y-axis, which are equally divided on the two lines, respectively marked as 1, 2, 3, and the coordinate 1, 2 is a point on the X-axis and 2 on the Y-axis.

A set of straight lines or lines used to define a coordinate system. The position of a point on the coordinate axis is uniquely determined by a coordinate value, while the positions of points on other coordinate axes are uniquely determined by a coordinate value, and the values of other coordinates on this axis are zero.