Describe the Vannis's dance pavilion. How is the pavilion central to the plot and conflicts in book 2?

In the beginning of summer, some Italians (the Vannis) come into town and set up a dancing pavilion in a vacant lot. They begin giving dancing lessons to children, and people start to gather and congregate around the lot. Now there is something for people to do and somewhere for them to socialize. Dancing becomes a city-wide craze, and every Saturday night there is a late-night dance. Jim goes all the time, as do many girls and boys from the country. At this point, Ántonia, Lena, and Tiny become known as "the hired girls" and are always at the dances too. This becomes a problem. Although the dancing craze catches on very quickly, dancing during this time period is generally associated with frivolity, moral decline, and loose women.