It is either just at the elem. I think the way you can serve both groups is to discover a topic that all levels need. However, with such a diverse group, the presentations will never be satisfying. I suggest that you organize small groups. Each group chooses an area to study and learns with depth and through hands-on experiences.
Groups can come together and share their knowledge.
This exchange is neat, for it helps teachers decide what they might choose. Charles - Laura, how often do you suggest teacher study groups meet. I suggest that study groups meet instead of faculty meetings. Several schools I consult at hold these study group meetings 2 times a month. The principal writes up administrative notes for the faculty who read these in advance.