Grammar · Clauses, Connectors & Sentence Style
Time Clauses (When, While, Until, As Soon As)
Four small words that tell you when things happen. Learn them with the film Night at the Museum, where everything wakes up after dark.
Grammar › Clauses, Connectors & Sentence Style › Time Clauses (When, While, Until, As Soon As)
The rule in one sentenceUse when and as soon as for a moment in time, and while and until for a longer stretch of time — something going on, or something that continues up to a point.
About the film
Night at the Museum is a family comedy from 2006. Larry Daley needs a job, so he becomes the night guard at a big museum in New York. As soon as the sun goes down, the museum comes alive, and a dinosaur skeleton runs around while Larry tries to keep everything under control.
What does it do?
A sentence can have two parts: the main action, and a part that tells you when it happens. That second part starts with a time word.
when and as soon as point to one moment. “As soon as” is stronger: the second thing happens immediately. while and until talk about a stretch of time. “While” means during that time. “Until” means up to the moment something stops.
Look at the first and third tiles. Each one shows a single moment. The other two show a period of time: while he isn’t looking, and all night up to the morning.
Larry reads the notes when he arrives. Larry reads the notes while he waits.
In the first sentence, he reads at one moment: his arrival. In the second, the reading and the waiting happen together, over a period of time.
Visual guide
Teacher Teddy’s illustrated guide to this rule is being drawn — the full swipe-through infographic will appear here soon.
How to make it
when / as soon as — a moment
When the sun sets, the exhibits start to move.
Larry doesn’t feel safe when the lights are off.
The time word stays the same in a negative sentence.What happens as soon as the sun goes down?
Put the question in the main part.while / until — a stretch of time
The tiny cowboys ride around while Larry is busy.
Larry can’t go home until his shift ends.
“Not … until” is very common.How long does he stay? Until the museum opens?
“Until” answers “how long?”.When to use each one
when / as soon as — one moment
while / until — a length of time
Words that help: moment or stretch of time?
These time words work in the same way. Learn them in two groups.
when / as soon as → a moment
while / until → a stretch of time
Common mistakes
❌ When the sun will go down, the museum will come alive.
✅ When the sun goes down, the museum will come alive.
After a time word, use the present, even for the future.
❌ Larry stays in the museum while the morning.
✅ Larry stays in the museum until the morning.
“Until” shows the end point. “While” needs a subject and verb after it.
❌ The monkey took the keys until Larry wasn’t looking.
✅ The monkey took the keys while Larry wasn’t looking.
The two things happened at the same time, so use “while”.
❌ As soon as it gets dark the dinosaur starts to run.
✅ As soon as it gets dark, the dinosaur starts to run.
When the time part comes first, put a comma after it.
One more thing
This part is a little harder. You can come back to it later.
No “will” after time words. When you talk about the future, the main part can have “will”, but the time part stays in the present. This is true for all four words.
❌ Larry will stay until the sun will come up.
✅ Larry will stay until the sun comes up.
✅ I’ll watch the film as soon as I finish work.
Practice: choose the right time word
Eight questions. Choose one answer. You get the answer, and why.
1. ___ Larry opens the door, he sees a dinosaur skeleton.
One clear moment → when.
2. The monkey takes the keys ___ Larry is reading.
Two things at the same time → while.
3. Larry has to work ___ six in the morning.
Up to an end point → until.
4. ___ the sun goes down, the museum comes alive.
Immediately after one moment → as soon as.
5. When the sun ___ tonight, the statues will move.
Use the present after a time word, even for the future.
6. Don’t leave the museum ___ the new guard arrives.
Not before an end point → until.
7. ___ I was walking home, it started to rain.
A longer background action → while.
8. I’ll text you ___ the film starts.
Immediately after one moment → as soon as.
Your turn
Choose one ending. Then listen to your sentence.
Every sentence here is correct. Pick the one that is true for you. Say it out loud too!
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