You might find you need to be more specific with this question as there are lots of activities that typical American families engage in that are depicted in Act II. What precisely are you referring to? Is it having breakfast? Is it two parents discussing their children? One possibility is the way in which Linda and Willy talk about money and their lack of it. Note the way in which Linda is shown to be responsible for the housekeeping and her quick ability to calculate money. It is she that needs to inform Willy and keep him on track about the money they need for such things as the Insurance, the payment on the refrigerator and the last payment on the mortgage:
All told, about two hundred dollars would carry us, dear. But that includes the last payment on the mortgage. After this payment, Willy, the house belongs to us.
Note the way in which this quote shows that Linda is taking over responsibility for aspects of the family which normally the man is responsible for. This highlights the way in which Willy is increasingly withdrawing from real life and not fully engaged in the aspects of day to day living, meaning that Linda is having to take over some aspects, such as financial management.