Common mistake: “The class starts in eight o'clock.” — Correct: “The class starts at eight o'clock.”
We use 'at' for clock times, 'on' for days and dates, and 'in' for months, years and seasons.
at / on / in
Preposition
Used for
Example
at
clock times & night
at 8, at night
on
days & dates
on Monday, on July 5th
in
months, years, seasons
in July, in 2026, in summer
The class starts at eight o'clock on Monday.
Sofía was born in July, in 1990.
The shop is not open on Sundays.
Ben doesn't work at night.
What time does the class start? Is it on Monday?
When is your birthday? In December?
Is the class at nine? Yes, it is.
Is the party on Friday? No, it isn't.
Practice
The class starts ___ nine o'clock. (at, on, in)
My birthday is ___ December. (at, on, in)
We use 'on' for days of the week: 'on Monday'.
The party is ___ Friday. (day)
Sofía was born ___ 1990. (year)
Find the mistake: I wake up in six o'clock.
Find the mistake: My birthday is on July.
The class is at nine. — Turn it into a question.
What time do you have English class? (Use 'at'.)
Listening
Kenji: When is our English class, Ben?
Ben: It's on Monday, at six o'clock.
Kenji: And the exam?
Ben: The exam is in December, I think.
Kenji: Perfect. And your birthday?
Ben: My birthday is on July 5th. Don't forget!
Reading
Sofía has a busy week. She has meetings on Monday and Wednesday, always at nine o'clock in the morning. In the evening, at about seven, she cooks dinner. Her English class is on Thursday. Her favourite time is the weekend: on Saturday she rests, and in the afternoon she visits Abuela Carmen. In summer, she takes a long holiday.