I have read this story many times now, so I'll share with you my thoughts when I first read it in 8th grade.
My teacher first went around the room and passed out folded slips of paper. When instructed, we all had to open the slips, and we found that some people had dots on their papers. Mrs. Powell told us that people with the dots were winners of a lottery. You can imagine the dismay of the rest of us. What did they receive? Money? Extra credit? Homework passes? We were jealous.
And then Mrs. Powell asked us how we knew they'd been randomly chosen to receive something good. What if winning a lottery was bad?
She then passed out the short story.
Already, the title had taken on an ominous tone. The first time you read the story, you are likely focused on the positive connotations with lotteries. Money, cars, pools, vacations—luxuries you don't currently have. But within a few paragraphs, something seems to be off in this little town. There is a dark undercurrent running through the details as the townspeople begin to gather. Take this sentence, for example:
They stood together, away from the pile of stones in the corner, and their jokes were quiet and they smiled rather than laughed.
Stones in the corner? What's that about? And why is everyone so subdued? Something seems a little off. Old Man Warner's adage about "Lottery in June, corn be heavy soon" seems to indicate some sort of impending sacrifice, heavy in its superstitious tone.
As the action progresses, the darkness builds. Tessie clearly doesn't want to win this lottery, and she is even willing to sacrifice her own married daughter to lower her own chances of being selected.
But when I read this story the first time, I truly did not see the ending coming and particularly not the way even Tessie's own family turns to kill her; someone even hands her youngest son "a few pebbles" so that he can participate. Thus, our teacher showed us the danger in both blind traditions and in failing to consider the true danger in situations, like a lottery, which at first resound with only positive connotations.
I hope this helps you rethink the way you felt as you finished reading this story the first time. Good luck!