Last Sunday night our church mission team that had just returned from El Salvador gave their report in the service. About fourteen people went, mostly adults but a few teens.
In my opinion this is the way that mission teams are best handled for teens. Those who went, went with their parents. It was a great bonding experience, as several parents have told me, and the young people worked right alongside their parents and the other adults. There were enough of their own age so that they could feel like they weren't alone; however, there were not so many teens that they were able to join in cliques, have their own private jokes, and depend on each other instead of reaching out to the people and learning about the culture.
When a large youth group goes on a mission team, just the young people with their sponsors, I believe that for the majority of the teens it is really just a glorified youth group trip - at a huge financial cost.
A group of teens went on a trip to a European country (most not with parents). There were a lot of adults on the trip, but a very large group of teens. When they returned I was concerned about the stories that they had to tell, because they had lots and lots of free time which they spent just sitting in the plaza of the main town. The next school year when I had some of those young men come to talk about that country to my geography class, and asked them what they most got out of the trip, they responded "Watching girls." I was greatly dismayed by that, and that is when I started thinking through the matter of teen missions trips.
Several years ago my school sent several groups to China. I think that about 10% of those who went really got the benefit and the burden that such a trip should entail. One young man came back and said that the best part of the trip was "the sauna in the hotel." I believe that most who went (they ranged from 8th to 10th graders) were not mature enough to really recognize the huge privilege and opportunity that was afforded them by being able to take a trip of that magnitude.
I went to Haiti at age 21 with a group of college-age students. I was profoundly affected by that trip - to the point that it opened my eyes to missions for life. College-age students are different - they have the maturity to see the needs and to have their hearts affected. But I really think that high school teens who go on trips do much better in the scenario at the start of this post.
If we had it to do over again - that's the way we'd send our children on missions trips. We'd go with them, in smaller settings, and we'd all get the benefit together. Not to mention the wonderful bonding experience of being on a mission trip with our teens.