How does Junior compare the families of the students at Reardan and on
the rez?

The day after deciding to transfer to Reardan, Junior finds Rowdy in the Wellpinit tribal school playground and tells him he is transferring to Reardan. Rowdy thinks it’s a bad joke and starts to get mad. Junior tells Rowdy to transfer with him, but Rowdy hates Reardan. Reardan is the only team to have beaten Junior and Rowdy’s 8th grade basketball team, and Reardan throttled Rowdy and Junior’s football and baseball teams too. Junior led Wellpinit against Rearden in the Academic Bowl, and Wellpinit lost 50 to 1. Junior was the only one to know that Charles Dickens wrote A Tale of Two Cities. The Rearden kids, Junior says, “were the best of times.” Rowdy realizes Junior is serious and turns away from Junior. Junior touches Rowdy’s shoulder, and Rowdy turns back and shoves Junior. Rowdy calls Junior a slur and Junior says his heart breaks. Junior tells Rowdy to come with him and touches Rowdy’s shoulder again. Rowdy punches Junior in the face, and, while he’s lying on the ground, Junior realizes Rowdy has become his worst enemy.

Explanation:

not concrete, existing in thought or as an idea but not having a physical or concrete existence

in what passage i'm sorry but i don't see anything there.