Collaboration with grade 9 students ... is it possible?

Students in my classes have been asked to create study groups and answer a daily group question daily for the past three weeks. As I look at the group responses submitted mainly through google docs, I am noticing a trend. The majority of the responses that are completed show work, but no real collaboration. They have approached this like a project where everyone does a piece, and then it is combined together and submitted it. No where is their any indication that they have collaborated in any way - no double checking of each other's answers, editing of each other's work. Students who are overly concerned for their mark in many cases have opted not participate in a group and chose to complete the question entirely on their own rather than have to deal with low functioning group members.



So what is the best way to encourage collaboration between students? Do they even know what collaboration is and what it would look like? Has anyone out there had successes in creating collaborative environments in their classroom?