Prepositions are short words used to link words together to indicate time, place, or direction.
The three prepositions in, on, and at are used to indicate both time and place in different contexts.

There are some exceptions when using in & on with transportation.
In |
On |
in a car |
on a bicycle |
in a truck |
on a bus |
in a helicopter |
on a plane |
in a wheelchair |
on a boat |
in a canoe |
on a skateboard |
in a wagon |
on a train |
in a taxi |
on a horse |
Here are some of the most common errors:
Incorrect |
Correct |
My birthday is |
My birthday is in June. |
I arrived |
I arrived on time. |
She worked |
She worked at the hospital. |
I heard the song |
I heard the song on the air last night. |
We could smell the delicious meal |
We could smell the delicious meal in the air. |
We have a meeting |
We have a meeting at 5 p.m. |
She saw an article about it |
She saw an article about it in the local newspaper. |
Some prepositions can be used to create different contexts.
Here are some examples:
She is in the elevator.

Meaning she is inside the elevator.
She is at the elevator.

Meaning she is near or in front of the elevator.
My friends and I are still in school.

Meaning we are attending school: we are students.
My friends and I are still at school and we will leave soon.

Meaning we are at the physical location of the building
We are in the hotel.

Meaning we are staying inside the actual building.
We are at the hotel.

Meaning we are at the location of the hotel.
Ben Affleck played the role of Matt Murdock in Daredevil.

Meaning in the movie Daredevil.
Charlie Cox played the role of Matt Murdock on Daredevil.

Meaning on the TV show Daredevil.
I read it in the New York Times.

Meaning in the newspaper.
I read it on the New York Times website.

Meaning online.
Nina, the character used in some of the examples, was inspired by the American singer, Nina Simone. To learn more about her colourful life and work, visit this National Women's History Museum page.