Lesson 2 · How AI Learns
How a high overall score can still hide serious mistakes.
A big accuracy number looks impressive. But accuracy alone can hide the mistakes that matter most.
Suppose 99 out of 100 emails are not spam. An AI that lazily says "never spam" is 99% accurate — and completely useless, because it never catches a single scam.
High accuracy, zero usefulness.
5 more parts in this lesson
Walkthroughs, code labs, mini-games and the checkpoint quiz unlock when you buy the course.