As all the other kids finished eating and filed out of the room, Canada's top young basketball star approached Johnson with a question. Where should he put his dinner tray of dirty dishes?
"He's a good kid, he was obviously very well-raised," Johnson said. "He volunteers for stuff, he's such a nice kid. These kids have a lot of things thrown at them, but he's a level-headed young adult."
Johnson, the most successful coach in North Carolina high school basketball history, is head coach of the boys East team for Wednesday's 36th McDonald's All-American game, in which Wiggins will be front and centre as this year's top-ranked high schooler in the U.S.
The teams practised for an energetic two hours at a Chicago high school gym in front of a couple dozen cameras and a row of some 50 clipboard-toting scouts — most of them from the NBA.
"Yeah, the second practice was good, interacting more with the players, I'm getting to know their game, they're getting to know my game," Wiggins said afterward.
His game wasn't flashy, he was more quiet confidence.
The Canadian travelled the lay-up line tossing down a couple of two-handed dunks that looked effortless, leaping so high his chin was level with the rim. He stepped out to drain smooth threes, and during a particularly vigorous up-and-down drill, he ran the court with the long fluid strides of a sprinter — a genetic gift from his Olympian mom Marita Payne-Wiggins.
"He's excellent off the basketball, and I really like the way, when he gets the ball, he keeps his head up and he looks and sees the whole court, he's not just looking to score he's trying to make everybody better on his team," Johnson said. "I think as we get more opportunity to watch him, I think everything you hear about him is true."
Johnson ran the players hard for a good couple of hours, and the sweat-soaked high schoolers were up for the task, sprinting hard, banging under the basket, diving for loose balls.
"We're all competitors," Wiggins said. "We know we're all the best in the country so we just want to prove that, that we've got game and we're competitors."
Former Toronto Raptors Antonio Davis and Dee Brown were among the spectators at practice —their daughters Kaela (Davis) and Lexie (Brown) are playing in the girls' game. The former pros straddled the curtain that divided the boy's from the girl's practices, but spent most of the morning watching the boys, marvelling at the ease with which the game's top young talent could execute one play or another.
"When you look at a player you look at athleticism, their skill and then just their knack for the game. You can check all three of them off when you talk about this kid," Davis said of Wiggins. "It seems like he has another motor, which means he's just going to continuously get better. I can't wait for him to get onto that college stage and then to the pros where he can really blossom into the kid that I think he's going to be."
Davis laughed when asked if he played in the All-American game as a high schooler.
"I wasn't that good in high school," said Davis, an NBA all-star.
"Me neither," Brown added laughing. "I was a late bloomer. Me and you were late bloomers."
Unlike most of the players in this week's game, Wiggins hasn't announced where he'll attend college, and his eventual choice has become the source of much speculation.
The 18-year-old gets asked about his choice constantly, and bristled Monday when he was asked about it again.
"Been good. Same old," he said on the recruiting process. "No pressure on my part to make a decision."
When asked about his timeline for an announcement, he responded: "I'll do it when I'm ready."
He's visited Kentucky, Florida State, North Carolina and Kansas, with Florida State — where both his parents went to school — and Kentucky are believed to be the front-runners.
Johnson, who has led Greensboro Day School to seven state titles, said wherever Wiggins winds up, he'll be able to step into the college game seamlessly.
"He knows the game of basketball, his basketball IQ is high and that's great for a kid that young," Johnson said. "So wherever he goes, he's already going to be a couple steps ahead of where the normal freshman will be at that stage."