Working memory is fairly small. If you do not have something to connect it with, you can remember 7 +/- 2 chunks of information.

Think about a number like 3425936547546.

Remembert that number.

Now if I took that number and put it into smaller chunks it would be much easier to remember:

342- 593 -654 -7546

Think about that the next time you ask a person to remember a list before doing something. It is a lot easier to do if you chunk it in a familiar way.