Should I do a group project on my own? If so, how? Recently in one of my courses I have been assigned a task to be done in small groups (of 3 people). It turns out not to be too long (especially with some previous knowledge that I had), so over the course of an evening I have done roughly 60-70% of the work and the remainder would probably go even faster for me. 

However the task was a group task, so I would feel that it could be quite inappropriate to just do all of the work and leave my other two friends nothing to do. I wouldn't like to make them feel left out and I wouldn't like to come across as a know-it-all. At the same time, I know that thanks to said experience not only will I need less time to complete the work, but also it is quite likely that the quality will be higher, potentially leading to a better grade and so benefiting all three of us.

Whatever I decide to do, I think I'll probably finish the task just for educational purposes, so the way I see it I can do one of those:


Tell them that I have the task complete. Apart from the disadvantages mentioned above they may feel compelled to also do all of the work, but forcing them to do so is absolutely not what I intend--if they also want to do so for educational purposes then they are of course welcome to, but I'd prefer to avoid them feeling like they have to do more than their fair share of work.
Pretend like I've only done some parts of the work and assign the "missing" pieces to them. First of all, lying about such matters seems to be a silly solution and also I feel like it could be easy to get caught and eithet be in worse position than 1) or have to lie more. Second of all, as I said when they complete their parts, it is possible that I'd feel obliged to make some changes to their work, potentially changing enough that it stops to look like their work, for us to get a better grade, which would be in all of us' best interest, but that would bring out some of the issues from 1)


How should I approach this topic, how should I communicate my ideas in the best possible way? Again, I don't want them to feel I treated them wrongly, but a the same time I wouldn't like our grade to suffer (in one of previous homework tasks I did give in even though I knew I was right at some points when discussing our solutions before turning them in, since I didn't want to come across as the smartass correcting everyone on everything, but our grade did turn out a bit lower then I would've gotten, had I turned all those tasks in by myself)
A group project in class isn't the same as an assignment at a job.  The teacher doesn't need this project done and isn't paying you to do it.  The project is assigned for your benefit and it was assigned as a group project because not only is course material to be learned but also teamwork skills are to be honed.  Use this opportunity to practice working with a group.  Hone your interpersonal skills and see how good you can make the result in spite of having less skilled teammates.  That's really the point of group projects.