What are the circumstances here? Why is this person asking you to help not doing so themselves? Is this a social/acquaintanceship situation or that of a directive within a job or area of responsibility? The situation with the students sounds like the latter; that you have been placed in a position of leadership. If this is so, I don't interpret it as 'helping' rather that of providing some direction. If this is the case, I think approaching the situation from a standpoint of "This is what we are going to do....." is the way to handle it. Divy up and delegate some of that authority an tasks amongst those subordinate to you.