We play basketball (in?) every PE lesson.

HongkieI think it is wrong to put the word "in" there. Am I correct?

No. Sorry. You are wrong.

CJ

Thank you, CalifJim.

How about the following sentences?

1. She calls me every hour.

2. She calls me in every hour.

3. She listens carefully to the teacher every lesson.

4. She listens carefully to the teacher in every lesson.

5. She sits next to me every lesson.

6. She sits next to me in every lesson.

1. She calls me every hour. OK.
2. She calls me in every hour. No.
3. She listens carefully to the teacher every lesson. No.
4. She listens carefully to the teacher in every lesson. OK.
5. She sits next to me every lesson. No.
6. She sits next to me in every lesson. OK.

The ones with units of time work differently. every day, every month, eve

Thank you.

I was confused because I took the word "lesson" as a unit of time. We can say "during the lesson" and "every lesson", just like we can say "during the day/hour" and "every day/hour".

Yes, I can see how this can be confusing, but "lesson" would be classified as an activity, not really a unit of time. Other words in this category are "concert", "picnic", and "meeting", and the more general preposition that often works for these is "at". In any case, you can't just leave the preposition out with these.

She asks questions at every lesson.
She sits next to me

It is a very clear and thorough explanation. I appreciate it a lot.

Thank you very much, CJ.