Start from zero — the basic math you need before everything else
The coordinate plane is two number lines crossing at right angles. The horizontal one is the x-axis; the vertical one is the y-axis. They meet at a point called the origin, written (0, 0). This grid lets us give every point a precise address.
The two axes split the plane into four regions called quadrants, numbered I to IV anticlockwise from the top-right. Each has its own sign pattern: in quadrant I both x and y are positive; in II x is negative and y positive; in III both negative; in IV x positive and y negative.
Think of the plane as a map, with the origin as your home. East (right) and North (up) are positive; West (left) and South (down) are negative. The four quadrants are like compass corners: quadrant I is north-east (both positive), II is north-west, III is south-west (both negative), and IV is south-east.
▶ The Coordinate Plane