I was a teenager once, that's how I know.
The "if it only helps one child" bit is getting a little tiresome though, isn't it? Time, effort and money are limited resources that should be spent in the most effective ways possible, not the least.
Meth came around a little after my time. I can't speak to that with any authority other than even the stoner friends I've had, who may smoke a little pot now and then, even *they* regard crystal meth as "bad medicine".
I'll admit that I don't know what would work better, but apart from being fatalistic I am *realistic* that the folks that are going to try meth are going to try it regardless of being told it is "bad".
Okay, so you know yourself. Are you really suggesting that every teenager thinks, believes, and acts the same way you did?
And how do you know this is the "least effective" method of discouraging drug use? Since you're an expert, go ahead and list the top, say, 30 methods and rank them by effectiveness.