at, on, and in for time

Learning outcome

You can choose at, on, or in for a clock time, a day, and a longer period.

Concepts and reasons

at is for a point of time. at 6 o clock. at noon. at midnight. at night. on is for a day or a date. on Monday. on 5 May. on Sunday morning. The day pulls the part of the day onto on. in is for a longer period. in May. in 1998. in the morning. in the afternoon. in the evening. in summer. Night is the exception among parts of the day. The exam pair is at night, not in the night. A day plus a part of the day stays with on: on Monday morning. Do not write in Monday morning.

Worked examples

1. The train leaves at 6. A clock time is a point, so at.
2. We met on Monday morning. Monday is a day, so on stays even with morning.
3. She was born in May. A month is a longer period, so in.

Common traps

in the night is the form this exam rejects. Use at night. in the morning is right when no day is named. on Monday morning is right when the day is named. Do not swap those two. A year takes in, the same way a month does. in 1998. Not on 1998, and not at 1998.

Practice questions

1. The shop closes ___ 9.
2. I will see you ___ Friday evening.
3. They reached home ___ night.

Answers and explanations

1. at. 9 is a clock time.
2. on. Friday is a day, and Friday evening keeps on.
3. at. The pair is at night.

Analogy

at is a dot on the clock. on is one square on a calendar. in is the whole month or the whole year around that square.

Quick reference

• at: clock time, noon, midnight, night.
• on: days, dates, and a day plus morning, afternoon, or evening.
• in: months, years, seasons, and the morning, the afternoon, the evening.
• at night. Not in the night.