This is within the first few minutes of Chapter 10:

Ace sits down next to Laura in the school lunchroom and we see Laura's food tray is the only one on the table. Ace calls A Plus over and does a bad Captain Kirk impression, after which we now see 3 food trays on the table. As Ace, A plus and Laura get up and leave the table, once again Laura's food tray is the only one on the table.