Describe tone in Shirley Jackson's "The Lottery" and "The Possibility of Evil."

Both stories have a bright, simple, everyday tone that provides a sharp contrast to their subject matter. Both tell stories of the evil that takes place in very ordinary, middle-class settings, the last places you would expect wickedness to unfold.
"The Possibility of Evil" is told, up until towards the end, through the eyes of Mrs. Strangeworth, a woman who uses bright, cheery language. She wants things to be "dainty" and "fresh." She loves her roses and enjoys cheerfully greeting and chatting with her neighbors. She completes her simple tasks, such as going to the grocery store, just like a completely ordinary person.
Her seemingly bright outlook on life and the happy tone of her voice is at odds with her great capacity to think and do evil. Because her heart is secretly dark, she believes evil is everywhere, and so she creates evil by sending out poison pen letters. One, to the mother of an infant, implies the child is an "idiot" and says sweetly but spitefully:

Some people just shouldn’t have children, should they?

Mrs. Strangeworth is able to convince herself that her evil is a way of doing good:

The town where she lived had to be kept clean and sweet.

Likewise, the people in the village in "The Lottery" think they are doing good while they are, in fact, doing evil. They believe stoning one member of the community will ensure a good harvest. No matter how much science seems to say otherwise, and even though other villages have abandoned their lotteries, this group of people persist in this barbaric practice.
As with "The Possibility of Evil," the tone of "The Lottery" is simple, bright, and ordinary, as if this were just another normal village event. As with "The Possibility of Evil," the story opens on a beautiful day, described as

clear and sunny, with the fresh warmth of a full-summer day; the flowers were blossoming profusely and the grass was richly green.

From the tone of this opening, there is no reason to expect a murder is about to take place.
The lottery is described as very mundane, something to get through so people can go home in time for "noon dinner." Ms. Hutchinson almost forgets and dries "her hands on her apron" as she arrives. These ordinary details, as in "The Possibility of Evil," create a tone that makes the horror of what is about to happen all the more acute.
Both stories show how a bright facade can allow people to lie to themselves about their own hidden aggressive impulses and the evil they do to their neighbors. The tone represents the false front people put on that hides what they are inside.