Hmm, that's a fair question. I tutored high school kids (14-17) for a while, and I would generally tailor things to their interest.
Basically, I tried to relate the math to solving a real problem they might be interested. Limits to money problems (e.g., could you retire on a Million dollars? Now take into account inflation, interest, etc)., differentials to sports/computer-games (plot the trajectory of the ball), random riddles, etc.
I'm not really sure how well that would translate to younger kids though ... My elementary school aged nephews/nieces tend to enjoy geometry problems (find the pattern ...), 'shortcuts' (FOIL, etc), and morphisms, but I fear my experience with kids that young is too limited to draw any general conclusions.
Basically, I tried to relate the math to solving a real problem they might be interested. Limits to money problems (e.g., could you retire on a Million dollars? Now take into account inflation, interest, etc)., differentials to sports/computer-games (plot the trajectory of the ball), random riddles, etc.
I'm not really sure how well that would translate to younger kids though ... My elementary school aged nephews/nieces tend to enjoy geometry problems (find the pattern ...), 'shortcuts' (FOIL, etc), and morphisms, but I fear my experience with kids that young is too limited to draw any general conclusions.