Nutrition definately factors in. Also exercise! There was an Australian study that won a prize that showed Fish oil and evening primrose oil combo to be of considerable help. Tutoring helped my nephew recently. My brother-in-law who is in his fourties now was greatly helped when he was a child by lack of pressure from his dad to have good grades(a psychologist figured it out after some time that dad's expectations were causing an unknown stress) back in the 70's.
So yeah, stress, nutrition, exercise, supplements, all helpful. I also personally had an idea awhile back: I was reading that regular tea has a stimulant similar to caffeine. But it is milder and it doesn't spike/fall quickly; it lasts for a long time. I wonder if it would be helpful as a natural stimulant for kids...but not in the evening, might effect sleep.
It would be cute if we all had children having tea and crumpets for breakfast,

yes? Well, even if it didn't help, the antioxidant benefit in tea couldn't hurt! I'm glad to hear you are drinking your green tea addprogrammer