This is a duplicate of an often asked question on this site. Policy says it cannot be closed unless an answer is accepted here as well or the original poster comments that the ID is correct. So, for what it's worth, this story is
Ray Bradbury's All Summer In a Day
The story is about a class of schoolchildren on Venus, which in this
story is a world of constant rainstorms, where the Sun is only visible
for one hour every seven years.
One of the children, Margot, moved to Venus from Earth five years
earlier, and she is the only one in her class to remember sunshine,
since the Sun shone regularly on Earth. She describes the Sun as "a
penny", or "like a fire in the stove", and the other children, being
too young ever to have seen it themselves, do not believe her. She is
bullied and ostracized by the other students and is locked in a closet
down a tunnel.
As the Sun is about to appear, their teacher arrives to take the class
outside to enjoy their hour of sunshine and, in their astonishment and
joy, they all forget about Margot. They run, play, skip, jump, and
prance about, savoring every second of their newly found freedom.
"It's much better than sun lamps!" one of them cries.
Suddenly, a girl catches a raindrop in her hands. Thunder sounds, and
they start to cry and run back inside. At this point one of them
remembers Margot, who is still locked in the closet. Ashamed, they let
her out of the closet, standing frozen, embarrassed over what they
have done, and unable to "meet each other's glances."
The precious Sun has come and gone and, because of their despicable
act, Margot, who loved the Sun the most, has missed it.
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