How does Arnold's reluctance to cooperate with his mother at the beginning of the story foreshadow the story's main event?

Arnold's getting too much for his mother, Bet, to handle. His serious learning disabilities are making it increasingly hard for Bet to raise him properly, so she's decided to put him in an institution. On the morning that Arnold's due to be institutionalized, he senses that something's not quite right and starts acting up, refusing to eat his breakfast.
Things don't get any better when Bet tries to dress him. Arnold makes the whole process as difficult as possible, willfully refusing to wear the brown hooded corduroy jacket that his mother's just fetched from the closet. Eventually, Bet's able to get Arnold out the door, fully dressed and carrying his little suitcase, but it's been a real struggle.
Arnold's stubbornness and lack of cooperation foreshadow how he'll behave once his mother drops him off at the institution. Although he seems quite placid at first, Arnold lets out a loud, terrible scream as his mother walks down the hospital corridor. This makes Bet feel uneasy, so much so that she just wants to get out of the place as soon as possible and catch a train home. There's a sense of urgency in her voice as she asks the taxi driver if he can get to the train station in a hurry. Bet wants to move on with her life as quickly as possible, both literally and figuratively.