Leaping into atonal music may be too big a leap for kids. I'd suggest Charles Ives as a bridge. He mixes chords to cause exciting dissonances. Take a look at his organ arrangement of "America." It's wild and crazy and dissonant and wonderful. Better still, find some concert in which it's being performed live on a monster organ. Ives' "America" is about as exciting as the grand finale of Respighi's Pines of Rome.

I'd say once Ives' music is palatable and enjoyable to you, then it's easier to listen to atonal arrangements. You've rescrewed on your ears by then through Ives.