Group activity is a way to get the works done fast. A task requires many skills and a single person can't have all the required skills. So if there are different people in a group with different skills, the group will be able to do the task without depending on the third person. So the constitution of the group is also important. If all the members are of the same skill set, the result may not be as expected. There will be a difference of opinion on the same subject as the experts are from the same line. The group leader's role is very important. He should not be biased and should encourage all the people equally and there should not be any favouritism. If he is not an able leader the whole work will become a waste and the team may fail in its attempts. I know many leaders who tried to help the people who are not doing good at the cost of hard-working members which failed. Because of such leaders, many organisations suffered and lost many able persons. So group work will be good only if the leader is good and an able person.