At the Life In Student ministry blog, Tim posted his reasoning for keeping High School and Jr. High combined.
I agree with his assessment. I grew up in a ministry that had a combined big group mid week and then more age specific sunday school. The big gathering on wednesday nights were some of my favorite times as a Jr. Higher because I saw people older than me actively engaging their faith, and maybe our group was unique (i hope not) but I always felt that the older kids were very inclusive with the younger ones.
What do you think?