and resentful of her because

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.

Therefore, Margot possesses specific, tangible memories of the sun and its positive qualities (e.g., warmth, luminosity, and life-giving powers that produce flowers) that her classmates sadly lack. Instead, the only time when they experience fleeting memories of the sun is at night when they are sleeping. Unlike Margot, they cannot even imagine and enjoy the warmth, light, and beauty of the sun when they are awake. Upon waking, they hear only

the tatting drum, the endless shaking down of clear bead necklaces upon the roof, the walk, the gardens, the forests, and their dreams were gone.

The classmates also are jealous of Margot’s implied wealth and love from her parents.

There was talk that her father and mother were taking her back to Earth next year; it seemed vital to her that they do so, though it would mean the loss of thousands of dollars to her family. And so, the children hated her for all these reasons of big and little consequence. They hated her pale snow face, her waiting silence, her thinness, and her possible future.

Margot’s parents prioritize their daughter’s health and well-being over money and convenience. Whether or not the loss of so much money poses a hardship to her family, the fact that her parents are willing to sacrifice money and opportunity to return to Earth for Margot is significant. She has a “possible future” of potentiality and escape, while the classmates are trapped on Venus.

Fear of the unknown is another cause of bullying. The classmates seem unsettled by Margot’s claims of a sun. Even though a teacher compares the sun to something relatable, like a hot lemon, they cannot understand and thus doubt Margot’s authorship of her poem:

I think the sun is a flower,
That blooms for just one hour.

In order to control his fear of the unknown, one classmate denies the existence of it. When Margot insists that the sun will appear, the boy tries to shut her down while haltingly trying to garner support from the other classmates:

“You won’t see nothing! ... Nothing!” he cried. “It was all a joke, wasn’t it?” He turned to the other children. “Nothing’s happening today. Is it?”

They all blinked at him and then, understanding, laughed and shook their heads.

“Nothing, nothing!”

The only way the bully can take any anxiety out on Margot’s claim is to undermine it by turning it into a trick.

“All a joke!” said the boy, and seized her roughly. “Hey, everyone, let’s put her in a closet before the teacher comes!”

The classmates control Margot not only verbally, but also physically by shoving her into a closet. Their source of fear of strangeness—Margot—is extinguished. They no longer have to hear or see her.

The primary message of Ray Bradbury's "All Summer in a Day" is that those who are different are typically ostracized and singled out among their peers.

In the story, Margot is the outcast of her class because she was not born on the rainy planet Venus like her peers and thus remembers how the sun looks and feels. When Margot recalls her experience on Earth and describes the sunlight, the children attempt to silence and ridicule her. Margot is also a timid, unpopular girl who behaves in an aloof manner and does not interact with her classmates in a natural way. Margot's differences isolate her from her peers, and her unique experiences incite their jealously. They envy Margot because she has experienced the sun and will be leaving the depressing planet shortly.

On the only day in seven years that the sun shines on the bleak planet, Margot becomes the class scapegoat as her peers begin to torment her. Influenced by mob mentality, the children direct their envy, rage, and jealousy towards Margot and proceed to lock her in a back closet, where she misses the rare opportunity to see and feel the sunlight. Readers recognize that Margot's differences are the primary reason she is rejected and bullied by her cruel classmates, who refrain from exercising perspective and sympathy.

Through Margot's terrible experience, Bradbury is not only highlighting the cruel nature of children but commenting on the stress and anxiety of being different. He is saying that those who are different are typically ostracized or singled out at some point in their lives.

The message, to me, is about how someone who is "different" will always be singled out. Margot is different than the other children -- she's smarter, and more creative, but beyond that, she can actually remember living on Earth. She has memories of the sun, something the other children lack. In a sense, she is more authentically human than the others. This makes the other children jealous, and causes them to act out against her. When Margot is locked in a closet and forgotten about for the short time when the sun comes out, I think we have to consider this as more than simply a prank that has gone too far. The children are, in effect, appropriating (or even stealing) Margot's experience -- now everybody has the same memory of the sun as Margot. It's an attempt to erase what made her special. Kids will be kids, even on Venus.

The children learn that there are consequences to bullying.

In this story, a group of nine year olds on Venus lock one, Margot, in a closet during the one day a year that the sun comes out.  They feel terrible afterwards, learning that they actually do have feelings and are not immune from empathy.  Bullying can hurt both the bully and the victim.

On Venus it rains constantly.  In fact, the sun only comes out once every seven years.  The children in the classroom who are the subject of the story are all nine years old.  They do not remember the sun.  They were only toddlers.  However, they have a transplant from Earth in their class who does remember the sun, and this makes her an outcast.

She does not play in the other children’s games, and seems more obsessed than the rest with the sun.  She claims to remember it, because she saw it when she was on Earth.

And then, of course, 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.

Worse than this is the rumor that Margot might be going back to Earth in a year, where she will see the sun again.  The children’s jealousy of her is extreme.

The other children are cruel to her and ostracize her.  Since she does not play their games well or engage with them, they do not know how to interact with her.  They resent her and call her a liar when she describes the sun.  It is their way of protecting themselves because of their longing for the sun.

On the day the sun comes out, the children’s frustration with Margot reaches a peak.  They tell her it was a joke, and then lock her in a closet.

When the teacher arrives, the rain is stopping, and the children are so excited that they completely forget about Margot.  The teacher asks if they are all there, and the children respond that they are.  They enjoy their time in the sun immensely, and then ask the teacher if it will be seven more years before the sun comes out again.  This realization causes one of them to remember where Margot is.

What they have done to her comes crashing in on them.  Suddenly, they are no longer carefree children playing a joke.  The horror of what they have done devastates them.  They can’t move.  As the rain comes down, each of the complicit children looks at each other.

They stood as if someone had driven them, like so many stakes, into the floor. They looked at each other and then looked away. … They could not meet each other’s glances. Their faces were solemn and pale. They looked at their hands and feet, their faces down.

The story stops as the children let Margot out, so we do not know what they say to her or how she reacts, or if they were ever punished by the teacher.  The real consequences of their actions are psychological though.  They have to live with what they have done.  A little piece of their childhood is lost after this.  It is a terrible, tragic thing to destroy a person’s hope like this, especially when you have heartlessly targeted an innocent victim.

Mob mentality is a kind of common giving up of control, so that no one person feels like taking responsibility for his or her actions.  In this case, the children all acted together, with no one taking the blame.  The effect is heightened by the fact that the victim is the only one who is actually given a name.  The children are only referred to as “boy” and “one.”  The group of children acts as one, and no one stops it.  Yet once they realize what they have done, they are still children, and they regret it.  They have learned that they may have acted as a group, but each one has to live with what they have done.

Bradbury's underlying message in his short story "All in a Summer Day" is a warning that envy can lead to cruelty and that we should embrace other people's differences. In the story, Margot is depicted as a timid girl, who was born on earth and remembers the sun. Unlike her peers, Margot longs to see the sun again and can describe its appearance. There are also rumors that Margot will be heading back to earth soon, leaving her peers on the raining, gloomy planet. Instead of sympathizing with Margot and accepting her differences, Margot's peers become envious and begin to bully her. On the one day the sun shines on the gloomy planet of Venus, Margot's classmates lock her in a closet, where she misses the rare opportunity to step outside and experience the sunshine on Venus. The children's treatment of Margot is harsh, disturbing, and cruel. The reader sympathizes with Margot's difficult, tragic situation, which underscores Bradbury's primary message regarding the dangers of envying others and the importance of accepting people's differences.

The lesson, if any, that the children learned is not made explicitly clear. This choice on the author's part may be a deliberate understatement, intended to reflect the children's shock and silence as they realize the impact of their actions but are too ashamed to say anything. On the other hand it may be an ambiguity, intended to make it unclear what the children learned, if anything.

In summary, the children live on Venus, where the sun only comes out every seven years, for two hours; at all other times, it rains nonstop. None of these children are old enough to remember the last time the sun came out; today will be the first time they see it and appreciate it for what it is. Margot is the only exception; she moved to Venus from Earth very recently, and remembers the sun clearly. The other children reject her stories out of jealousy, and this combined with the constant rain cause Margot to become depressed and reclusive, further aggravating the bullying. They lock her in a closet before the sun comes out, mostly out of spite.

The children enjoy their time in the sun, but completely forget about Margot until it begins to rain again. When they are reminded, they all react in a similar manner; they are silent, looking at the ground, and move slowly. This seems to imply shame and remorse for what they've done, probably because they only understood the impact of seeing the sun after they had experienced it for themselves, and therefore realized what they had denied Margot. We might say that the lesson they learned was the true meaning of empathy.