Shirley Jackson's short story "The Lottery" highlights many different themes: violence and cruelty, custom and tradition, victim and victimization, and gender roles. Given the lottery is a tradition in the small town, many examples can be found to highlight this theme.
The children assembled first, of course.
The addition of "of course" shows knowledge of the narrator. It is included as if the reader should know this information already (given the tradition itself).
The original paraphernalia for the lottery had been lost long ago.
This quote shows that the lottery has been conducted for a long time, long enough for the original tools to be lost.
No one liked to upset even as much tradition as was represented by the black box.
This quote proves the lottery to be so much of a tradition that no one wishes to do anything which would change it.
The black box grew shabbier each year.
Here, this quote speaks to the timelessness of the lottery. Given it takes place every year, one comes to the conclusion that the box and the lottery are traditions of the town.
The people had done it so many times that they only half listened to the directions.
Again, the clue to tradition here lies in the fact that no one needs instruction any longer on the lottery. Instead, the townspeople only "half listen" to the directions.
"There's always been a lottery."
This line, spoken by Old Man Warner, proves to be the most solid fact that the lottery exists as a tradition and custom of the village. He tells readers that it has simply always existed.