What’s the Dif? (Vol. 1): When and While (Part 1)

(Originally posted October 1, 2010)

The basis of all human activity is time. It’s time to wake up. It’s time to go to school. My dad to me in high school: “If you don’t get up now, next time, I’m bringing the wet washrag.” (He only had to do it once. The feeling of a sopping wet, freezing cold washcloth in the face in the middle of winter will last a lifetime.) It seems like we never have enough time to do everything we want. Time can pass too slowly and too quickly at the same time. “I can’t wait for Friday.” “I can’t believe Christmas is here already.” (Or if you are a little kid: “It’ll never be Christmas.”)

Time is the basis for all verb tenses. Every day means you must use the present simple. Yesterday indicates the past simple. But since yesterday needs the present perfect. If you change the time, you must change the verb tense. However, conjunctions of time, like before or until, have nothing to do with verb tense.  They are just used to show the connection between two actions.

Two of the most common conjunctions can be very confusing. Today’s blog will try to demystify the ever-popular when and while.  These two are quite possibly the most aggravating conjunctions in English. They are so simple, but they are so easy to mix up.

When is a very general idea. Most often it is used to give less important background information. A clause with when can often be replaced with a simple prepositional phrase. For example:

  • I got contact lenses when I was in seventh grade.
  • I got contact lenses in 1978. (Don’t do the math!)
  • Farmers go to bed when the sun goes down.
  • Farmers go to bed at sundown.

In general, the verbs in a statement with when are most commonly used in the simple tense. For example:

  • My father got his driver’s license when he was fourteen. (True story.)
  • I will call you when I arrive at the airport.
  • I usually drink a cup of coffee when I get sleepy in the afternoon.

Notice that in the past and present (always true), the verbs in both clauses match. However, in the future, the verbs don’t match. The main clause is in the future simple tense, but the adverb clause (with when) is in the present simple tense. Also, notice that main verb with when is (usually) an instant action or linking verb

(There is one specific case when the continuous tense can be used with when, but that will be discussed in Part 2.)

While, on the other hand, is much more specific. The most common usage of while is to emphasize two actions happening at the same time. Either one person is doing two things at once or two people are working simultaneously. For example:

  • I always listen to NPR’s Morning Edition while I drive to work.
  • Last night, my wife washed the dishes while I gave Skyler a bath.
  • My father and I sat on the back porch drinking lemonade while my mother finished mowing the lawn. (It’s kind of a funny story, actually.)

Notice here that the verbs with while are continuous action verbs.

A common mistake with while is to assume that you always use the continuous tense (be + ~ing). This is NOT TRUE. Neither when nor while has any connection to verb tense. Verb tense is controlled by other words in the sentence, or understood times. In the above examples, always tells you to use the present simple tense. Last night tells you to use the past simple tense. In the third example, I am telling a story, so it is understood to be in the past. While has nothing to do with the time.

Maybe he best test for whether while is correct or not is the during test. The following phrases are all correct. (During is the preposition form of the conjunction while.)

  • while I drive to work = during my morning commute
  • while I gave Kimo a bath = during Kimos bath
  • while they were taking a test = during the test
  • while I was watching the movie = during the movie
  • while I was working = during my shift / during work

But the following pairs are very wrong.

  • when they woke up = during they woke up
  • when the bell rang = during the bell rang

It is true that sometimes either word, when or while, is ok. For example, imagine a student who spends her junior year in university abroad. When did Emma learn to speak Spanish?

  • Emma learned to speak Spanish when she lived in Madrid.
  • Emma learned to speak Spanish in 2004.

However, it would also be correct to say:

  • She learned to speak Spanish while she lived in Madrid.
  • She learned to speak Spanish during her year in Madrid.

The following hypothesis explains this case. When is used exclusively with instant action and linking verbs. Either when and while are (often) interchangeable with continuous action verbs. (You can use either one.)

I can get turned around by these two as quickly as anyone else. I can’t pretend that this is a definitive explanation. However, these rules/hypotheses seem to work (almost always).

But maybe this isn’t so difficult. Maybe it’s as simple as this.

  • when = in/on/at
  • while = during

Try it out and let me know if it works.


*Instant actions are actions that finishes very quickly, sometimes in less than a second. How long can you sneeze? How long does one clap continue? How long does it take to leave a room or close a window or turn off the lights? (Yes, I realize that clap, in this case, is a noun.)

The opposite of instant actions are continuous actions. People sleep for hours. People can study something for years. Marathoners can run for hours.

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