As a long-time junior high small group leader I have often felt frustrated by the very thing that frustrates most of my volunteers: Tangents! Oh, tangents....those wonderful diversions that we have tried to, but will never, get rid of.
MAYBE THAT'S OKAY!
Here's my simple thought on tangents: Go with 'em.
Seriously, my thinking is that any spiritual conversation among junior highers is good conversation. So, if in the middle of your enlightening study of Exodus, a 7th grader suddenly asks why bad things happen to good people....go with it. If your 8th grade girls are in the mood to talk about dating....go with it.
Tangents that have no spiritual value may need to be cut short and allowed to be explored at a later time, but tangents that are simply taking you down a different spiritual road than the one you planned can lead to some great discussion.