Well, a group task can be a bit annoying!
I have had a bit of trouble with the people in my group because they are either sick or can't make it. I have made the wikispace .
So I started by communicating to the group when we should meet. Because although we have two break weeks, still doesn't mean that we can't use that to our advantage. I also explained to them in the email that:

• What our task was: So to create an authentic task that will enable students to enhance their learning in the use of technology. The task that we came up with was to get students to create their own mould experiment and create their own blog and oral presentation to be able to show the whole class. (Prior to this we had also discussed this to group members that were there in the workshop- all I was doing was re-capping and for those who weren't there explaining to them what Michael and I did...)
• I also explained to the group members that they had to join the wiki. Therefore they had to create an account. This meant joining up for free and emailing me back with a username so that I could add you. i have to say that I'm disappointed in some of my group members as they haven't got back to me. So I kindly email Michael explaining that they haven't got an account yet and he said to let them come to us.....which I thought was true! WHY SHOULD I RUN AROUND AFTER THEM WHEN THEY HAVEN'T DONE ANYTHING TO HELP ME!!!
• I also explained to them what their roles were. For example what type of bread and type of conditions they were doing. I also asked then to kindly take a photo of their bread almost every day so they would have something to share with the group. I also divided up the roles. So my job was the lesson plans and Michael's was the teacher resources. I asked Kelly to do the Curriculum, so how does our task relate to the current curriculum.  I asked Lisa to take care of the student resources. 
• Finally, I asked them what days that we could meet up to discuss our group task and work on it as a group: I said that we might as well not change the time or the venue and go to the same place     at the same time next week.

I thought I was being completely nice about it. I was not being pushy or annoying I thought the way that I handled the email was reasonable and easy to follow.