WHEN & WHILE

We use when and while to talk about two things that are happening at the same time. 

What is the difference between when and while?
WHILE: Usually we use while when there are two long actions. 

WHEN: Usually we use when if one action is long and the other is short.

We use when if there are two short actions.

We use when if we talk about periods of our life (When I was 12 …)

1. The dog was barking. She was talking to her mother on the phone.
talking to her mother = long action
dog barking = long or short (Did the dog bark for a long time? Did it bark for a short time?)

It is unclear whether there are two long actions here. So we can use when or while.
The dog was barking when she was talking to her mother on the phone.
The dog was barking while she was talking to her mother on the phone.

2. She was doing the dishes. The telephone rang.
doing dishes = long action
phone rang = short action.

So we'd say,
She was doing the dishes when the telephone rang.

3. The alarm bell rang. He was sleeping.
He was sleeping = long action
alarm bell rang = long or short action (Did it ring for a short time? Did it ring for a long time?)

It is unclear whether they are both long actions. So we can use when or while.
The alarm bell rang while she was sleeping.
The alarm bell rang when she was sleeping.

4. It was raining. I was watching a movie.
It was raining = long action.
I was watching a movie = long action

So we'd say,
It was raining while I was watching a movie.

5. I saw lightning. I heard thunder.
saw lightning = short action
heard thunder = short action

So we'd say,
I saw lightning when I heard thunder.

6. She was driving to work. She heard the news.
she was driving to work = long action
she heard the news = probably a short action

So we'd probably say,
She was driving to work when she heard the news.