I have always believed that you learn just as much from fiction as nonfiction. Halfway through My Sister is a Serial Killer and I have learned that the Naira is the official currency of Nigeria (perhaps I should have known this already).
The dresses that you always see the women dancing in from the 1920s are called Flapper dresses. Ayoola makes and wears one in the book. Hers is made of gold beads. I think that somewhere in the back of my mind I did know this. Perhaps from The Great Gatsby