Having a 12 year old student as my son, I would probably start with the Wikipedia definition for link bait.
To write something so good on your site that people will list your site on thier website when they talk about that topic.
i relate link baiting to dating a little (LMAO)...neither of which I am any good at so I just stay away from both! No seriuosly...a good friend of mine introduced me to link baiting just recently...it's an interesting concept. But I still relate it to dating...this might work well for you...since we are talking about explaining the concept to a pre-teen boy It's nothing more than a hook...something interesting to catch the readers eye, hook them in...then it goes viral. Hope that Helps u...I'm a little cynnical today so...
People want to link to your site. That is a short definition of what is link bait. Like ... some webmaster tools, great articles, unique resources .... and stuff like this.
To create a good and interesting article that will catch the attention of the readers and probably view it more often...