I'm not at liberty to go into details but I just heard a tragic story that I can't get out of my head. If you are considering sending your innocent teenager off on a mission trip to somewhere like El Salvador, which is infamous for its violence ask a few questions of the representatives of the mission group. How are the volunteers housed and what steps are taken to ensure that no kid is left alone? Even if they give you a reasonable answer, do you really want your son or your daughter in a place where they are in constant danger and have to be guarded (by whom?) in order to be spared from robbery or rape? If you want your child to be acquainted with a little hard work and gratitude for what they have it's too, too late to wait until they are teenagers and you are foolish to send your child to a dangerous place for the sake of charity.
I beg you to instead send them to a mission in Appalachia, South Dakota or Mississippi. At the very least, if something bad should happen in the US you will be able to go to the police. In Latin America your son or daughter will be helpless, and at the mercy of possibly hostile, greedy or dangerous authorities.