"The students fight every day at school."

Translation: 학생들이 매일 학교에서 싸워.

[raycosm]

Does 매일 have to come before 학교에서?

[IchbinderFremde]

No. That doesn't matter.

학생들이 매일 학교에서 싸워.

학생들이 학교에서 매일 싸워.

매일 학생들이 학교에서 싸워.

All are okay above.

[Andreaming24]

I got it wrong because of that as well...

[nleconte]

Not necessarily, but it could.

[Andreaming24]

I got it wrong because of that, as well...

[D8amx]

what's wrong with 학생들은?

[jackisback7]

That is grammatical and I think it would be understood in context. But in this case "the students" makes it sound like a specific small group of students is being discussed, rather than just "students" in general. So 이 is used.