The first couple of weeks after the disaster, Calla Perkins was bursting with anger. She expressed her fury in ways she would regret. She sometimes hit and kicked her cats and dog. "I'm so angry I don't know what to do," her mother, Laurel Emery, said Calla told her. When Calla, who is 8, walked past a sign advertising World Trade Center pictures, she would kick it. She would carry her stuffed animals to the bathroom, announcing the trade center was falling and she had to get them to safety.
Then she calmed down. But recently, she has regressed. She is in second grade at Public School 89, near ground zero. Ever since her relocated class, minus about half its students, returned to the school building at the end of February, she has become very aggressive, reverting to behavior she displayed in kindergarten. She has been pushing and striking other children, and calling them names.
Fire trucks and smoke make her edgy. "I'm doing good sometimes," said Calla, who is getting counseling to try to smooth out her anxieties. "I'm scared of noises and sirens." But she was evasive about saying much more. "I feel bad when I talk about it," she said.
Eight months after Sept. 11, most children in New York seem to have bounced back and returned to rooting for the Yankees or Mets, flocking to "Spider-Man" or playing in their soccer league with the same childhood zeal they showed in living their lives before Sept. 11. But many others continue to struggle to find their old bearings. Sometimes they are seemingly carefree children. Sometimes they are living children's lives with adult worries.
The scope of the problem was underscored by a recently released study conducted for the Board of Education. It concluded that roughly 200,000 of the 712,000 public school children in grades 4 through 12 were candidates for some sort of mental health intervention — at least a visit with a mental health professional — because of the lingering trauma of Sept. 11.
Many behavioral changes showed up immediately after the attack — the 8-year-old girl who hid in her closet day after day, children who, at 7 and 8, resumed bed-wetting, children who simply stopped doing their homework — and then subsided.
But others have manifested themselves more recently, undoubtedly compounded by the other cruel dramas of the past months — anthrax, the Rockaways plane crash, the Middle East bombings.
Every time one 5-year-old girl hears a sad song on the radio, she asks, "Is that about the World Trade Center?" Some of Calla's classmates have taken to carrying good luck charms to school, hoping they will ward off the world's evil.
Other children harbor revenge fantasies, mental health experts say. There are children who speak of suicide, though it's not easy to trace the precise origins. After all, children had problems before 9/11, too.
Children often disclose their emotions differently than adults, and many do not talk about them, psychologists point out. With the passage of time, the connections become more elusive.
Many children will recover with time alone. Left to fester, however, trauma can have a long life. Claude Chemtob, a psychologist specializing in trauma and disaster who has been working with some of the downtown schools, said disaster research showed that without treatment, symptoms could persist for years. He said, for example, studies indicated that children showed effects from a 1972 flood in West Virginia as long as 20 years later.
The most keenly affected children in New York, of course, are those who lost a parent. But many others, including those who neither live downtown nor go to school there, still suffer, in ways large and small.
"As more people recover and are back to normal, the kids who are slower to recover know if they complain of their fears, they will be avoided," Dr. Chemtob said. "And so they go underground."
And, as Robert Abramovitz, chief psychiatrist of the Jewish Board of Family and Children's Services, added, "One thing we know from other conditions where kids are privately suffering: if you take a history from parents, they're not terribly aware of how depressed the kid is."
Melanie Chu was sipping multiple hot chocolates with her friend after the school day. She is 8 and in third grade at P.S. 89. Melanie has had her difficulties processing the shock of 9/11. Her ongoing fears sometimes drive her to hide beneath a table in class, her mother, Carol Chu, said. When she goes to her piano lessons, she sometimes acts up and ducks under the piano. She dreads being alone and insists on sharing her brother's room. He is 10 and less enthusiastic about it.
Not only downtown children feel convulsive changes in their lives.
One quiet afternoon a few weeks ago, Kate Brassel, 17, was sitting with several friends in the library of the Convent of the Sacred Heart School on the Upper East Side, where she is a senior. A helicopter flew by outside the window. They all became unnerved. The incident caused them to do something they really had not done, which was talk about the effects of Sept. 11 on them.
"We had sort of forced ourselves not to think about it personally, because the kids downtown had it so much worse," Kate said. "It sort of seemed selfish to say, `Oh, poor me,' when those other kids had it so much more traumatic. I mean, I live 100 blocks away."
But they found that they, too, had been rattled.
She said she significantly curtailed her social life all winter. "I didn't go see plays or go out to dinner or go shopping," she said. "Normally I did it a lot. A lot of things seemed pointless and unimportant. A couple of friends were the same way. Now I've started to force myself to go out. I've started to reintroduce myself to having fun with friends."
Her friend and classmate, Rima Ibrahim, who lives in Park Slope, Brooklyn, said, "I feel like that day took away some of my innocence." Things that once seemed significant, like her school uniform's being perfectly pressed, no longer do. "I know that my friends feel more anxious, like we always need to be worried, that we are not invincible and anything can happen to us when we least expect it," she wrote in an e-mail message.
At P.S. 253 in Brighton Beach, Brooklyn, which has a sizable Muslim enrollment, considerable hostility has arisen between non-Muslim and Muslim children, not so much right after Sept. 11, but right now. Shirley Pierantoni-Pineiro, the director of the After-School Corporation's program at the school, says fear and tension are palpable among the students. Children become damp-eyed and do not seem to know why. They want to call their parents. "They say, `Mommy, are you O.K.?' " she said. " `What about Daddy? Are you sure you're going to pick me up?' This is happening now."
So many children cannot make the bad thoughts stop.
Nicole Goodkind, 12, who lives in Battery Park City and is in seventh grade at I. S. 89, said, "At night I have thoughts that come into my head like Osama bin Laden will come into my room. I know that won't happen, but I still have those thoughts. They started about a month ago. Whenever I hear a loud noise, I can't sleep. I know it's not rational, but I had a dream two weeks ago that Osama bin Laden made a kid throw up all over downtown. And I'm scared of dead people. I have my grandfather's ashes in our home, and that scares me."
She added: "When I hear a loud noise, I have to open my blinds and look out. Sometimes I think there's an atom bomb."
Joe Begley mentioned how Sept. 11 had become an unwelcome demarcation point for him. He is 14, lives in Battery Park City and is in eighth grade at Our Lady of Pompeii School in Greenwich Village.
"I use 9/11 as a marking point," he said. "Have I done something before 9/11 or after? When did I start guitar? That was after. When did I start art classes? That was before. It's weird. It's on my mind all the time."
He went on: "I take great caution in everything I do. When I'm in a very populated area, I look around at the people."
His brother, Peter, 12, said he was squeamish about tunnels. "I used to love tunnels," he said. "Now I imagine dying in a tunnel because it's blown up." He feels tense when he goes through the tunnel to visit his grandmother in Queens. "I imagine the water coming in and dying a slow death," he said.
His sister, Kelley, 11, says she has been averse to planes. When the family discusses vacation possibilities, her response always is, "That's fine, as long as we go by train." The other day, her mother suggested Italy. Kelley said, "Now how do you get to Italy by train?"
Taurean Malofsky had her eye on the clock. It was close to 6:30 in the evening. At last, time for bed.
She is 15 and goes to Manhattan Village Academy on 23rd Street. She lives in Washington Heights. She did not know anyone killed in the trade center. Still, she has found herself profoundly affected. In particular, pity for the children who lost parents has suffused her heart.
To a large extent, Sept. 11 has blighted her life. "I can't have fun," she said. "I feel that way. I just can't have fun."
She finds herself unable to ride the subways alone. She used to keep an activity-packed teenage schedule. She hung out after school. She went shopping and to movies with friends. Bedtime was around 10.
Now she usually hurries home after school, tackles her homework and turns in by 6 or 6:30. When friends invite her out, she begs off.
"I just don't want to do anything," she said. "I fail to see the point. I don't want to be outside my house too much. I can't be at anyone else's place for too long. I have a fear of being outside. The only place I feel I can be safe is here."
Awful dreams haunt her. In one dream, her school was blown up by planes. In another, her mother walked into water and died.
She wishes she could snap out of it, but she cannot. "I try to focus on being happy," she said. "I'm trying to not be depressed. As a teenager, there are so many things I could do. It's crazy to waste my time."
She has not seen a counselor. She said she did not want to. Instead, every day she confides her painful thoughts to her diaries.
She does not know when the demons will relax their grip on her. Meanwhile, she seeks solace in her bed. Sleep never comes easily. During the 20 minutes or so it takes her to nod off, she always says a prayer.
"I'm really scared," she said. "I don't want to go to sleep and wake up and something else happened. I really don't want something else to happen. And so I pray, Please let me wake up and be alive. Please don't let anything else happen."