Two Layers, Read Separately

You'll learnto describe how a curve changes using two separate reads — its direction, and its concavity.

As the input moves, the output responds. Describing that properly takes two questions asked in order: which way the output goes, and whether its changes are growing or shrinking. They are independent layers, and answering the second from the first is the most expensive habit in Unit 1.

8 STEPS · 6 QUICK CHECKS · DIRECTION · CONCAVITY · Δ TABLES · v2

direction is the output; concavity is the rate

Before you start

What you're looking at

A single curve linking an input to an output. As the input slides to the right, the output responds and the marked point traces the curve.

The question

Which way does the output move — and are its changes growing or shrinking as it goes?

Watch for

First, just whether the point rises or falls. Then, separately, whether each step of change is bigger or smaller than the one before.

Step 1 / 8