One parent, Laurie Frost, said: “I am not convinced that even the most masterful teacher  and we have many of them here in Madison  can teach effectively to the full range of ability and need we currently have in our public schools. Not at the same time in the same classroom.”

Budget cuts this year, with more expected next, could undermine the fine balance. “The danger,” Ms. Passman said, “is it becomes us versus them. And that’s not good for anybody.”

Ms. Moss hopes not. Garner used to run away and collapse on the floor in despair if he had to change rooms. The schools, she said, have patience with him. In elementary grades his teachers learned to tell when he was about to explode from pent-up energy, and let him leave to ride an exercise bike. In sixth grade, he had his first class without an aide, band.

In ninth, when he went out for cross country, he’d get lost during practice, so the district hired a college student to run with him until he learned his way.

He has always been in general education classes, but usually with an extra teacher or aide. This year, he will be on his own in most classes, including English, chemistry and personal finance. He’s a familiar figure, striding home from school with his swim bag, backpack and alto sax.

His development has always been uneven. He rides the bus downtown to his father’s law office, but can’t tie his track shoes; at meets his teammates tie them. Summer days start with cross-country practice at 8. (In summer, running and swimming are with club teams made up of his high school classmates.)

One day when his mother went to pick him up after practice, he’d run the 1.7 miles home. He rested up and watched a tape from the previous night’s Milwaukee Brewers game.