ACCELERATION IS THE CHANGE IN VELOCITY OVER TIME, JUST LIKE SPEED IS THE CHANGE IN DISTANCE OVER TIME. 

Have you ever been on a roller coaster? They start off slow. You can move around and lean forward in your seat with almost no energy, but when they start to speed up, like at the first drop, you get pushed into the back of your seat until you’ve stopped speeding up.

That change in velocity over time is acceleration. 

Some cars are often advertised based on how fast they can accelerate. You might hear the term 0 to 60 in 5 seconds. This means the car can go from 0 mph to 60 mph in just 5 seconds. But that’s just a change in speed. We have to add a direction to make it velocity.

Acceleration can be positive or negative. A positive acceleration means that the object is speeding up.  

A negative acceleration means that the object is slowing down.