Choosing the correct preposition in English can often be tricky, as the incorrect preposition can not only impair understanding but, in some cases, completely change the meaning of what you are trying to say.
The following feature will focus on the use of IN, ON and AT when speaking about place/position.
We use ‘in’ when we are talking about being specifically inside a larger area. For example:
I am in the classroom (the classroom is larger than me)
The classroom is in the school (the school is larger than the classroom)
The school is in Edinburgh (Edinburgh is larger than the school)
We use ‘on’ when we talk about a surface. For example:
The cup is on the table (the table is a surface)
The picture is on the wall (the wall is a surface)
The teacher writes on the whiteboard (the whiteboard is a surface)
So far, we have learnt that we use in for a larger area and on for a surface. However, let’s look at the following examples:
I’m on the bus
I’m on the train
I’m on the plane
I’m in the car
I’m in a taxi
One reason for this is that the bus, trains and planes are usually public, whereas cars and taxis are private.
Another reason for this is that buses, trains and planes have a pre-determined route (we don’t decide where it goes, it follows a specific route). You can’t for example, ask a train to stop outside your house. It is restricted to the tracks. You also can’t ask a pilot to land the plane in your back garden. However, you can decide where to go in your car or in a taxi.
We use ‘at’ when we talk about a point. For example:
I’m at the bus stop (the point where the bus stops)
Who is at the door? (the point just outside the door)
We also often use at when we are talking about public buildings/services/conveniences:
I’m at the supermarket
I’m at the dentist
I’m at the pub
WHAT IS THE DIFFERENCE BETWEEN ‘IN’ AND ‘AT’?
The following sentences are both correct:
I’m in the swimming pool
I’m at the swimming pool
Why is this?
The first example means you are actually in the water and swimming, whereas the second example could mean you are in the changing room, having a shower or getting dressed.
When we use in, we are specifically inside something (the swimming pool in this case), where at is much more general.
With that logic, you can say “I’m in the supermarket”, if you are INSIDE the supermarket or “I’m at the supermarket” to either mean you’re INSIDE or JUST OUTSIDE the supermarket.
Please note, this only applies to buildings/services/conveniences (you’re unlikely to find someone IN the door, they’re more likely to be AT the door).
This is a very brief overview of these prepositions. As with many language points, the important thing is PRACTICE, PRACTICE, PRACTICE. The more practice you get, the more natural your use of prepositions will become.