Margot causes the main conflict in Ray Bradbury's "All Summer in a Day" because she writes a poem that describes what the sun will look like when it comes out.
This is what Margot's poem said: "I think the sun is a flower / That blooms for just one hour."
Immediately after this, a boy named William expressed his disbelief and accuses her of not writing that poem.
The next day, the conflict continues out of jealousy. Margot had been on earth until she was five, while the rest of the children were born and raised on Venus.
"...the biggest crime of all was that she had come here only five years ago from Earth, and she remembered the sun and the way the sun was and the sky was when she was four in Ohio. And they, they had been on Venus all their lives, and they had been only two years old when last the sun came out and had long since forgotten the color and heat of it and the way it really was."
Because of this jealousy, the kids push Margot into a closet and lock her up forcing her to miss the sun's brief appearance on the always raining planet.