A lot of my work with Youth With A Mission is about mobilising young people, children and families into cross cultural mission, usually, due to life stages involving schools and colleges, for the short term of between two weeks and three months.
Such short-term missions teams come under fire for being a waste of money, better spent on people in need and not a flight, 'flash in the pan' ministry that has no bearing on long term change in a given area, and largely about the young person or child having a great experience. While these criticisms are understandable, they are also perhaps based on misunderstanding, and done well, the fruit, influence and impact of such trips can be vast and significant.
Firstly, it is true that it will be significant for the young person on the trip. For them, there is a significant discipleship element to the trip. They will encounter God's love for others in a new way and they will perhaps be forced to rely on God in a way they never have before. Not only that, but when under pressure in a new, sometimes uncomfortable place, with a team of people, your character is put under a magnifying glass and a whole lot of ugly is exposed some of which you can't ignore!
My musings. Opinions my own, and potentially not that thought through!