When and while are often confused by language learners because they are similar. In Part 1 we discussed the basic differences between them. To summarize:
- When is used to establish a specific point in time.
- When can be replaced by words like in, on, at, if or as soon as.
- Statements with when often have instant action verbs or linking verbs.
- While is used to show two actions happening at the same time.
- While can only be replaced by during.
- Statements with while usually have two continuous action verbs.
When and while can also be used to show an interruption, meaning one action stops because of another action. With interruptions, you are telling a story, these sentences are always written in the past. The most common way to show an interruption is with while.
- The fire alarm rang while the students were taking a test.
- I fell asleep while I was watching a movie.
- One day, while I was working in a convenience store, a motorcycle caught on fire outside on the street. (True story.)
When you describe an interruption, one verb is a continuous action verb. The other is an instant action verb. The continuous action verb is always in the past continuous tense. (This is probably where the “while = continuous tense” idea comes from.) The order of information in the sentence is determined by what is most important.
Interruptions can also be described with when. Very often, the word suddenly can be included. Notice the difference in order.
- The fire alarm (suddenly) rang while the students were taking a test.
- The students were taking a test when the fire alarm (suddenly) rang.
- I fell asleep while I was watching a movie.
- I was watching a movie when I fell asleep.
The verb tense does not change. The continuous action (take or watch) is written in the past continuous tense. The interruption/instant action (rang or fell asleep) is written in the past simple tense.
However, the organization of the information changes. With while, the continuous action is the adverb clause (after while) and the instant action is the main clause.
With when, the information is switched. The continuous action is the main clause and the instant action is the adverb clause (after when). Also, the adverb clause with when is always last.
Like most things with language, when and while to show interruptions can be confusing at first, but it gets easier with practice.