Here's why:

* Speed tells us how fast an object is moving.

* Velocity tells us both how fast an object is moving *and* in what direction.

Think of it like this:

* You might drive a car at 60 miles per hour (speed).

* But you could be driving 60 mph north (velocity) or 60 mph south (different velocity).

Velocity is a vector quantity, meaning it has both magnitude (speed) and direction.