Prepositions of Time

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
General Dates “Night”
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.”

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General Time

  • Time of day: In the morning/afternoon/evening/night…
  • Time of year: In Spring/Winter/Summer/Fall…

General Date

  • 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.


clock-1196246Now 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.

Check out this dominoes game from to test your understanding create some more sentences!

How do you remember the differences between in, at and on? Tell us in a comment!

Happy Writing!

That, Which or Who?!

My sister, who I love a lot, has a big sweater that has many holes, which get bigger every time she wears it.

Have you ever been confused by when you use that, which or who to describe the subject of your sentence? So were the students in the English class I am currently teaching! However, with the handy chart below and some easy steps, it’s easy to figure out which word to use in your descriptive clause.

Subject Punctuation   Type of Information
Place/Thing  None That Defining

Which Non-defining
Person None Who Defining



STEP 1: Find the Subject

The sentence above has two different subjects that are described by clauses. The first subject of the sentence is “my sister,” then the second is “a big sweater.”

STEP 2: Determine the Type of Noun

Is the subject of your sentence a person or a place/thing? The first subject, “my sister” is a person noun while the second noun, “a big sweater” is a thing.

STEP 3: Determine the Type of Information

Defining information is anything that is necessary to provide so that your reader can understand what the subject is. Meanwhile, non-defining information simply gives extra detail and could be taken out of the sentence easily. For example, the information that the sweater has many holes is necessary to identify this specific sweater. On the other hand, the fact that the holes get bigger each time your sister wears the sweater does not define the sweater and is extra detail.

STEP 4: Choose Your Word Using the Chart. Click here to download it from our Resources page.

STEP 5: Add Punctuation.

While you might get by when speaking using any of these words, it’s best to be correct in writing 🙂 This is even more important when adding in the correct punctuation. Non-defining clauses should be surrounded by commas “,” the punctuation marks that indicate a pause in the sentence. These marks also indicate that the clause could be excluded from the sentence and still make sense. For example, in the sentence above, you could take out “who I love a lot,” and the sentence would still be grammatically correct!

In this type of sentence, which will always come after a comma, but who either has a comma before or does not depending on whether the information is defining or non-defining. 

Have questions? Contact us, we’d love to hear from you!