Prepositions govern and typically precede a noun or pronoun and express the relation of this to another word or element within the clause. For example:
The chicken is in the freezer. <<< Here, ‘in’ is the preposition.
We first met at Alan's barbecue. <<< Here, ‘at’ is the preposition.
Is the brush on the table? <<< Here, ‘on’ is the preposition.
‘At’, ‘in’, and ‘on’: prepositions of place
One of the primary ways that we use ‘at’, ‘in’, and ‘on’ is to help us explain the location of things. For example:
Mary will meet you at the corner of your street.
You left your book in the bathroom.
There is a picture on the wall.
We’ll start by discussing ‘at’. As a rule, ‘at’ is used to tell us the specific point or location of the noun:
He’s waiting at the bus stop.
Simon is at his desk.
I work at a pet shop.
‘In’ is used quite differently. What it does is tell us that the noun is in an enclosed space, often surrounded or closed off on all sides. For example:
Simon was sat in a green room.
Mary was riding in the forest.
The cat was in a box.
‘On’ is used to tell us that the noun is located on a surface, either attached to something or touching it:
Hector stood on the table.
Mavis was seated on the floor.
Albert sat on the chair.
Sometimes, these prepositions can be used interchangeably, depending on the desired emphasis. For example, we might say either:
She’s at the shop.
She’s in the shop.
Both are grammatically correct, but the former focuses on location, whilst the latter explains the type of building that the ‘she’ in the example is in.
In, on, at: Be careful!
It’s important to note the use of ‘at’ and ‘on’ when we’re referring to addresses. As you would expect, we use ‘at’ when we’re providing an exact address. For example:
Her favourite bakery is at 123 Cake Street.
He lives at 20 Oakleaf Avenue.
She’s studying at the University of Leeds.
However, we do not use ‘at’ for addresses without house or building numbers, so rather than saying…
She lives at Street Lane.
…We would say…
She lives on Street Lane.
‘At’, ‘in’, and ‘on’: prepositions of time
We can also use prepositions when we’re referring to time, not just to place. For example:
He goes to bed at nine.
I was born in December.
He goes horse riding on Saturdays.
Once again, the rules regarding when we use each of our prepositions vary.
Let’s start with ‘at’. We use ‘at’ for a precise time, so we might say:
I woke up at 11.30am.
I had lunch with my grandmother at the weekend.
I only said goodbye to my friends at midnight.
We would use ‘in’, on the other hand, to refer to periods of time, such as months, seasons, or years:
I visited Greece in July.
I haven’t smoked in three years.
Samantha travelled to Russia in winter.
Now let’s look at ‘on’. ‘On’ is used to refer to days and dates:
A lot of shops don’t open on Sundays.
I took my dog to the vets on Friday.
I spent time with my family on Christmas Day.
In, at, on: Be careful!
It’s important to note this exception to the rule: we do not use ‘at’, ‘in’, or ‘on’ before the words ‘all’, ‘any’, ‘each’, ‘every’, ‘last’, ‘next’, ‘one’, ‘some’, ‘this’, or ‘that’, even where these are followed by a time expression, so although we might say…
I’ll do it in the morning.
…We would still say…
He hasn’t been here all morning.
Here are a couple of additional examples for you:
He went on Sundays.
He was there each Sunday.
He was there at the weekend.
He was there last weekend.
Now let’s see whether you can apply what you’ve learned. Here are three exercises to test your newfound knowledge. Give them a go and see how you do.