Things can move.  They can move faster, they can move slower, and they can change direction.  A change in speed or direction is called acceleration.

Things can move through space.  How fast or slow something moves is called its speed.

A car is going slowly.  It starts to move more quickly.  It is moving fast.  We walk.  We start to run.  We are moving faster.

We can walk one way.  We can turn around and walk another way.  The way we walk is called direction.  A car can turn.  When it turns it changes direction.

Things can change.  Something can go slow and then go faster.  This is a change.  We can grow tall.  This is a change.  We can paint a wall.  This is a change.  A change means something becomes different.

Something can be going fast and then slow down.  When it slows down it is called deceleration.  Deceleration means to move slower.