Most of us faced with this situation would try our damndest to ring that bell. If we failed once, we would not simply quit. We would feel obliged to try the next in order to save that next child's life. Teaching children how to behave is every bit as important as ringing the bell is in our fantasy scenario. You go on and try to teach the next child the lesson because it matters.
Children are different from adults.
They must be sheltered and guided because they have not yet learned all they need to know to make mature decisions and bear the consequences and responsibilities that flow from those decisions. We must try our best to teach them that some actions are better than others. We must teach them that sex for recreation is wrong, that love is more precious than any passing physical feeling and that the cost of not abstaining from sex until they are older and wiser is horrendous. Sure, some of the kids will fail to get the message. It is criminally irresponsible to condemn them all to lives of poverty, despair and possibly AIDS, in a disintegrating society because of the irresponsibility of these few.