Background: Jane and Michael are two kids in an upper middle class family in late Victorian England. Their parents have placed them in the care of various nannies whom they have terrorized. Along comes Mary Poppins, who is magical and amazing while completely proper.
In this scene. Mary Poppins has … tricked… the kids’ father into taking them to work with him at the bank (their name is Banks too…). Michael has decided to bring along his tuppence (two cents) he has saved because he wants to buy bird crumbs to feed the birds. Instead, his father and bosses try to convince Michael to put the money into the bank. There, they claim, this two cents will build all kinds of amazing things, added with everyone else’s money. Kind of like how Carnegie justified using his money for good– now that he had busted heads of striking workers, he was going to give them libraries!