Start from zero — the basic math you need before everything else
A graph is a picture of a function. Left to right is the input (x); up and down is the output (y, or f(x)). To read a value, find your input along the bottom, go up to the curve, then read across to the height. That height is the output.
The shape tells a story. Where the curve goes up as you move right, the function is increasing; where it goes down, it's decreasing. A high point where it turns from rising to falling is a peak; a low turning point is a valley.
A graph can be a hike's elevation: distance runs left to right, height runs up and down. Where the trail climbs, the curve rises (increasing); where it drops into a valley, the curve falls (decreasing). The summit is a peak; the lowest dip is a valley — exactly the graph's turning points.
▶ Reading a Graph