Something that team 1629 did/does is...
Because not everyone is interested in ALL aspects of technology at the beginning of each year we do a brief over-view of most of them then the students devide into the different groups (electrical, programming, mechanical, etc.) then our mentors who are most fimiliar with those "sections" lead the groups, and the students and mentors work together in their seperate groups then once a week we "combine" groups to "put it all together"... It seems to work fairly well... It makes fixing the problems easier too because if its programming then you have "experts" working on it... Same with elect. mech. etc.
PS students can be part of multiple groups!
