Prepositions are definitely one of the trickiest parts of the English language and can be extremely frustrating to English language learners. When writing, you can take the time to double check how you use prepositions and get comfortable using the correctly with some basic rules that simplify when they are used. In this sense, time is used either related to time as it is measured on a clock, or time as it is measured on a calendar. In these circumstances, the most commonly used prepositions of time are IN, AT and ON.
So when do we use in vs. at vs. on?
|General Time||Specific Time||Specific Dates|
|Future Quantity of Time|
Let’s look at some examples…
The preposition “in” is used when looking at general chunks of time. Think of a calendar or a clock. If you are talking about a portion of the calendar or clock that is larger than its individual unit of measurement (a day or an hour/minute) you use “in.”
- Time of day: In the morning/afternoon/evening/night…
- Time of year: In Spring/Winter/Summer/Fall…
- Year: In 2016…
- Month: In May…
- Week: In the third week of May…
The exception to this description of using “in” for general chunks of time is with the example below. Notice how this use of “in” only relates to a future time. This is indicated by using the word “will.”
Future Quantity of Time
- In 5 minutes, the show will start.
- I will meet you outside your house in 3 hours.
- I will be done in a minute.
Now if you zoom in and look at time as it relates to the clock, we use “at” to talk about a specific time
- Hours: The concert starts at 7pm.
- Minutes: At 6:37am everyday, the rooster crows.
- Point in Time of Day: Cinderella had to run home at midnight.
- Activity Time of Day: We met at lunchtime to discuss the problem.
A confusing instance where both in and at can be used is with night. It is correct both to say:
- She woke up when she heard a noise in the night.
- She could not sleep because of the sound of crickets at night.
The difference is comes from when the action occurred. “In the night” is more poetic and often refers to something happening in the middle of the night at a specific instance (a noise). “At night” is then used more generally, to refer to something happening (the sound of crickets) during the whole night. This is the opposite of the usual use of in for general and at for specific.
Lastly, there is the preposition, “on,” which we use when talking about specific dates. This time, zoom in on the calendar to know when to use “on.”
- Days of the Week: On Tuesdays, she goes to English class.
- Dates: The last time she saw her cousin was on June 30th (or on the 30th of June).
- Holidays: Have you seen the big parade in New York City on St. Patrick’s Day?
Can you use all 3 in one sentence? Here are some examples:
- On Valentine’s Day, in 2005, she met her date at 6pm for dinner.
- In Spring, he went to a concert, on March 21st , at noon.
- She is going to call on Wednesday at 10pm, which is in exactly 24 hours.
How do you remember the differences between in, at and on? Tell us in a comment!