We only get to be kids once so have fun with it

We only get to be kids once so have fun with it.  If he's not into igloos, drop it and try something else. But don't tell him it’s a 'lesson'.  Just do something for fun.  Have a contest, whose ice cube will melt faster, yours in a glass of soda or his in an extra hot cup of cocoa. .  Try something like that.