This is in the Episode "Life in a Glass House" in the 2004 season where Dan Scott throws the Annual Basketball Banquet at his house. In the beginning, Haley is tutoring Nathan for an exam the following Monday and has finished the lesson. Before getting up, Haley puts the waist backpack over her head. Then when the camera cut to her again the backpack is off, and the just puts it on her shoulder. Then the camera come back again and its around her head again!!!! Oops