Please, correct my essay.

I think that it’s more effective that students for examinations alone. The reason is that if students make groups and study, they have different time to concentrate on studying. Some might stop studying halfway and want to do other things. In other words, studying in groups may prevent students who are eager to study from studying seriously. However, as far as students study alone, they don’t care about others around them. They can start studying whenever they want. They can choose time to quit studying. By studying alone, they can utilize time and study effectively, not being interrupted.