The slope of a curve

The question that powers all of AI

Training a model means adjusting its parameters to make the loss smaller. With millions of parameters, you can’t try every setting. You need to know, for each parameter: if I nudge this a little, does the loss go up or down — and how fast?

That “how fast does the output change when I nudge the input” is a slope. For a straight line it’s one number (Module 2). But for a curve the steepness keeps changing. This lesson is about measuring the slope of a curve at a single point. It’s called the derivative, and it’s the core idea of calculus.