Which three kids take Auggie on a tour of his new school?

The three students who take Auggie on a tour of Beecher Prep are Charlotte, Jack Will, and Julian. These three students were initially chosen by staff at Beecher Prep because of their reputation for being positive student leaders in their class.
During the meeting, all three students are surprised by Auggie's physical deformities. They had been prepped beforehand during a meeting, but did not seem to fully understand. Upon meeting Auggie, all three students are pleasant in front of the adults (Mr. Tushman and Auggie's mother). When the four kids leave to take a tour of the building, things begin to change.
Charlotte remains kind to Auggie during the tour of the school building. Jack Will, although somewhat rude at first, starts to defend Auggie after Julian begins to bully him. As is true throughout the entire school year at Beecher Prep, Julian bullies Auggie and is rude to him during the tour. He makes cutting remarks regarding Auggie's lack of school experience.

Before Auggie starts at Beecher Prep, his mom takes him to meet the principal, Mr. Tushman, and to tour the school. Mr. Tushman has asked 3 students, Jack Will, Charlotte, and Julian to give Auggie a tour. He reached out to them over the summer and asked them to be nice to Auggie since he was a new student with facial deformities. Mr. Tushman had told the 3 students about Auggie's looks, but it is still surprising to them when they see Auggie for the first time.
During the tour, Charlotte is very talkative, and shows Auggie many different classrooms. Jack is also friendly with Auggie, and that friendship continues once Auggie begins the school year. Julian was mean to Auggie right from the start, and he asked him direct questions about how his face got the way it did. Throughout the story, Julian continues to be a bully towards Auggie. Auggie's relationship with Jack is strained in the middle of the book, but in the end, Jack learns that true friendship is more important than popularity. Even Julian seems to accept Auggie by the end of the story.

The three kids that take Auggie on a tour are Charlotte, Julian, and Jack Will. Mr. Pullman, the principal, chooses these three students because they have a reputation for being kind and considerate. Prior to meeting Auggie, the three students have a private meeting with Mr. Pullman. During the meeting, Mr. Pullman informs the students of Auggie's condition.
Though Mr. Pullman does his best to prepare the students for meeting Auggie, the students initially react poorly to seeing Auggie's disfigurement. However, after spending the morning together, Charlotte, Julian, and Jack Will each become more comfortable with Auggie. Charlotte spends time asking him questions about his condition and life, and she quickly becomes friendly with him. Julian remains somewhat nervous and detached, but eventually he warms to Auggie. Jack Will, initially quite mean to Auggie, eventually stops teasing the boy. By the end of sixth grade, each of these three students has developed a unique, complex, and mostly positive relationship with Auggie.