After lunch break, the students were divided into three groups, during which...

[Tan Elaine]

After lunch break, the students weredivided into three groups, during whichthey discussed what they should do to improve the cleanliness of the school.

Is the comma needed? Thanks.

 

[Raymott]

After lunch break, the students were divided into three groups, during which they discussed what they should do to improve the cleanliness of the school.

Is the comma needed? Thanks.

Yes. And 'during' is wrong unless they were discussing this while they were being divided into groups.

 

[Tan Elaine]

Yes. And 'during' is wrong unless they were discussing this while they were being divided into groups.

As"during" is wrong what word should be used instead? Thanks.

 

[Rover_KE]

after

 

[LeTyan]

"improve the cleanliness of the school. " sounds wordy and pretentious. "make the school cleaner" is better.

---NOT A TEACHER---

 

[Tan Elaine]

after

Thanks, Rover.

After lunch break, the students were divided into three groups, after which...
Is the sentence OK, since it starts with 'After' followed by another 'after'.

 

[Raymott]

Thanks, Rover.

After lunch break, the students were divided into three groups, after which...
Is the sentence OK, since it starts with 'After' followed by another 'after'.

Why not? After breakfast, I dug the garden, after which I did some study, after which I ate lunch, after which I had a nap ..."
It's not elegant, but you can't use an inappropriate word to solve issues of elegance.

 

[Barb_D]

"improve the cleanliness of the school. " sounds wordy and pretentious. "make the school cleaner" is better.

---NOT A TEACHER---

I disagree that it sounds pretentious. There is nothing wrong with your suggestion but nothing wrong with the original.

Try this: ...groups and then each group discussed...