hmm..
from what I know......Past continuous is often used with while (duration) and when (moment). You also see the simple past being used with the past continuous, and when the action is brief, you �d use the simple past, if the action is much longer you �d use the past continuous.
What you �ve seen in a lot of exercises is this:
ex:When you entered the door, I was making breakfast.
>here you have one short action, that interferes with the long one...
OR
ex:I was making breakfast while you were setting the table
>here you have two long actions happening at the same time...
some teacher �s say if it follows "when" put it in the simple past and "while", put it the past continuous. And you can �t go wrong with that tip, but it �s not always the case.
ex: When Sarah was watching tv, Jill called.
hope that helps..