IMO learning eye hand coordination is the most important thing at that age and younger. When I used to coach that age group I never taught the strike zone. As a matter of fact we threw fewer strikes in practice but told them to swing at every pitch. As the season progressed they learned the strike zone because they were not successful at making contact out of the zone. In a game we told them to swing at the pitches that were easier for them to hit in practice, which is actually teaching the zone. You can teach a kid to walk but why take away his aggression. I'd rather lose the game and win for the long haul.