Math 1 · Unit 2 · Lesson 1 · part 4 of 8
The coordinate plane, and how to plot a point
Take two number lines and cross them at zero.
The coordinate plane, and how to plot a point
Take two number lines and cross them at zero. The one lying flat is the x-axis. The one standing up is the y-axis. Where they cross is the origin, the point (0, 0). Together they make the coordinate plane, and every spot on it has an address.
The address is an ordered pair, written (x, y). Ordered means the order matters: x is always first. To plot (3, 2): start at the origin, walk 3 to the right along the x-axis, then 2 up. Put a dot. Negative x means walk left; negative y means walk down.
A way to remember it: along the hall, then up the stairs. You walk sideways first (x), then up or down (y). The point (3, 2) and the point (2, 3) are two different places, so keep the order.