Past simple

Past simple shows us that action was in the past , not in the present.

postitive sentence

My parents called me yesterday.
I woke up early this morning.

negative sentence

My parents didn't call me yesterday.
I didn't wake up this morning.

question sentence

Did your parents call you yesterday?
Did you wake up this morning?

Past continuous

The past continuous shows us that the action was already in progress at a certain time in the past.

What are you doing at 8 p.m. last night? I was studying.
She couldn't come to the party. She was working.
Three years ago, we were living in my home town.

Past continuous and past simple

When we use these two tenses together, it shows us that the past simple action happened in the middle of the past continuous action, while it was in progress.

While i was studying, i suddenly felt sleepy.
I broke my leg when i was skiing.
As i was going to work, i saw an old friend.