I decided to try this because a lot of students shout out they agree or do agree with the answer.
Does this sentence need a comma before because?
No comma is needed in that sentence.
"they agree or do agree" is repetitive; delete one of those verbs.
Thank you
To determine if a sentence needs a comma before the word "because," you need to consider whether the sentence contains a dependent clause or an introductory phrase.
In this case, the sentence "I decided to try this because a lot of students shout out they agree or do agree with the answer" does not require a comma before "because" because the word "because" is introducing a dependent clause that explains the reason for the speaker's decision.
If, however, the word "because" was used to introduce an introductory phrase that does not depend on the rest of the sentence, a comma would be necessary. For example: "Because of the overwhelming support, I decided to try this." In this case, the comma is used to separate the introductory phrase "Because of the overwhelming support" from the main clause of the sentence.