One strategy I have used to gain the trust and respect of a group member who is already competent has been to ask them to share their expertise on the topic. If it is using a technology tool, I've asked them to share their experiences and describe any benefits or challenges using the tool. If the group member is willing to participate this gives them some ownership and allows them to realize that their knowledge is valued and respected. Another strategy that could be useful would be to identify those individuals before hand, and ask them to play more of a leadership role in planning, organizing and teaching the content for the group collaboration.
It is always a challenge trying to convince anyone to change their routine to incorporate new ideas. Developing that professional relationship through asking a lot of questions, actively listening to their responses, getting to know more about their own work ethics, philosophy, and priorities can help build trust and respect. If you already have this relationship established, introducing a new idea is better received and colleagues may be more willing to try out the suggestion. Respect, listening, and understanding go a long way, especially when implementing change. An effective leader has the ability to grasp the attention of the group, establish that trusting relationship, and finally lead them through change. Establishing this relationship requires time and effort. It is not something that just happens, it has to be established over time. Whenever the leader is going to suggest change, they also need to model that change prior to the suggestion. In order for the group to keep that trust, and be willing to change, they have to see that their leader has already embraced the change and is practicing what they preach.Implementing change is always a challenge, and a convincing stick can only drive that nail in so far. If you are the leader implementing change, find your team members who are already experts and convert them to leaders. Model that change, and develop respect and understanding. If you do encounter a bad apple in a group, develop some good "fogging" techniques to avoid those interactions. All these techniques do, is mask the complaint and flip it into something good. For example, your are the leader in a classroom and a student starts to complain "we've done this a million times, I think we get it already." Instead of defending yourself, you could calmly and compassionately say, "I understand your frustration, but not all of us have mastered this yet. If you're confident with your knowledge, maybe you can help me help the others?" In so many words you're saying..."here's a box of tissues for your issue." ( ~_~,) When all you did was to flip the complaint to a compliment to get them to become a leader. These fogging techniques work well to engage those who think they already know what your teaching.

