Even better is "See all those commercials in TV? They're all created by people trying to tell you what to do. You don't like being told what to do, right? So why let a stranger who just wants to make money off you tell you what to do?"
My parents gave me that speech when I was 5, before I was allowed to watch any non-PBS TV. It was remarkably effective; I just tuned out all the commercials, because I knew they were people trying to sell me things that I didn't actually want before I saw the commercial. It got so extreme, at one point, that my mom had to go the other way and say "Y'know, it's okay to spend money once in a while."
I will take your advice to the heart. It really speaks for the quality of the community here, to speak about marketing and advertising and its deplorable influence on the young developing mind.
And I say that because I have been there. I have been anxious, unhappy because of material posessions, wanting everything that is displayed vividly in glamorous ads.
And it is a bad place to be. I'm 22 years old and now I'm cured. It's been quite a journey to regain independent thought.
My middle school taught a class/game about detecting propaganda techniques. It was like a blind person being taught how to see the invisible. A superpower.
I have a hard time believing this applies generally. I've learned from 20+ years of the public getting on the internet that desire is so strong that it leads people to believe they deserve to have every desire fulfilled. You might just have exceptional children.
I mean I got in a little discussion on this very site where people insisted advertising is equivalent to force. That's clearly wrong, but it is also fairly illuminating.
Isn't it children that should be teaching us about that? :)