a vast improvement

The word "vast" means "really big". But "vast" is not a really common word. It's mostly used in a few situations and phrases:

• Use it when talking about outer space.

  The distance between us and the nearest star is so vast, it takes about 4 years for its light to reach us.

• Use it with the word "difference":

  There's a vast difference between playing with someone else's kids and having kids of your own.

• Use it with the word "majority":

  The vast majority of people in the world have never even ridden in an airplane, much less a private jet.

an improvement over (something)

When you're comparing two things, use the phrase "an improvement over ___" to name the thing that's older and not as good:

I hope this year's Christmas party is an improvement over last year's.

This example means that you hope this year's party will be better than last year's party.

the last (something)

There are two meanings of "last":

1. Something that comes at the end.
2. Something that came right before the current thing.

In the example above, "my last camera" means "the camera I had before this one". So it's meaning #2.

How can you tell the difference between meaning #1 and #2? It's usually easy to tell. For example, see if you can pick out which meaning is used in these examples:

My last girlfriend was a guitar player in a rock band.

I saved the last piece of the cake for you.

This is the last time I'm coming here! This place is horrible!