Hello Tessa-
I also use TBL in an OT curriculum, and I find that in groups larger than 5 each 
member does not become fully engaged. With the larger groups, it becomes 
easy for some to sit back and watch, rather than contribute. I would suggest 
smaller groups- they will bond again quickly.
Best of luck,
Cynthia Evetts
Texas Woman's University
School of Occupational Therapy