Being Part of the a......?

Once, I was part of a project group in Primary School and our performance in it will be reflected in our report books at the end of the year. Thus, it was a very important task. They were one member short but at the last minute, a person who did not have any group got allocated to our group.We did not really know him and my group members were quite reluctant to let him join However, we could not argue with the teacher’s arrangement. We then carried out the project while the other three members viewed me with a certain sense of skepticism. As we progressed with the project, they seemed to grow lazier and lazier, and threw  most of their work at him, he had no choice but to try to work harder and harder. However hard he tried,he never seemed to get the others to realize that he was the most hardworking person in the group.My group members did not treat him as part of the group,but ironically,he was the  one doing most of the work.
  I tried to help him, but was it peer pressure or my own greed,I'm not quite sure of.My group members,also my friends threatened to stop helping me in school if I continued to help the boy.My selfishness got the better of me, and wishing to keep the "friends" of mine, decieded to leave the boy alone.
  It was not surprising that a few months later, we did badly in the project. Our teacher approached us about it and was quite shocked to know what had happened.Punishment was of course given and I was quite remorseful about it.However,my groupmates were not happy about it and tried to taunt him.It was only after some pleading from me before they relented and stopped.But for the rest of the year,they teased him whenever they saw him.It is of course obvious that he alone could not have done the groupwork well,but somehow,they didn't seem to stop and think about that.
  This incident happened a few years ago and I have lost contact with the group mates who went to other classes.But I still can't help and think back and feel bad about how we treated the boy.In this school.where group work often takes place,I hope that if the same thing happens again,I will stand up against the black sheep and give every group mate the treatment they deserve.