Johnathon Carrington stands for a portrait at Dunbar High School, where he recently graduated as the valedictorian of his class. He is headed to Georgetown University, but he’s concerned that his high school education might have not prepared him well enough for college. “I don’t think I’m going to fail everything,” Carrington said. “But I think I’m going to be a bit behind.”

June 12, 2013 Johnathon Carrington stands for a portrait at Dunbar High School, where he recently graduated as the valedictorian of his class. He is headed to Georgetown University, but he’s concerned that his high school education might have not prepared him well enough for college. “I don’t think I’m going to fail everything,” Carrington said. “But I think I’m going to be a bit behind.” Jahi Chikwendiu/The Washington Post

Johnathon Carrington graduated Friday as the valedictorian of his neighborhood school, Dunbar High, and is headed to Georgetown University. But Carrington, 17, is nervous, and so are his parents. What if Dunbar — where truancy is chronic and less than one-third of the students are proficient in reading — didn’t prepare him for the rigors of college? What if he isn’t ready?

Johnathon Carrington graduated Friday as the valedictorian of his neighborhood school, Dunbar High, and is headed to Georgetown University. But Carrington, 17, is nervous, and so are his parents. What if Dunbar — where truancy is chronic and less than one-third of the students are proficient in reading — didn’t prepare him for the rigors of college? What if he isn’t ready?

Johnathon Carrington graduated Friday as the valedictorian of his neighborhood school, Dunbar High, and is headed to Georgetown University. But Carrington, 17, is nervous, and so are his parents. What if Dunbar — where truancy is chronic and less than one-third of the students are proficient in reading — didn’t prepare him for the rigors of college? What if he isn’t ready?

Johnathon Carrington grew up on the sixth floor of a low-income D.C. apartment complex, a building most recently in the news for a drive-by shooting that injured 13.

His parents told him early on that education could be his escape, and Carrington took them at their word. He graduated Friday as the valedictorian of his neighborhood school, Dunbar High, and against all odds is headed to Georgetown University.

But Carrington, 17, is nervous, and so are his parents. What if Dunbar — where truancy is chronic and fewer than one-third of students are proficient in reading — didn’t prepare him for the rigors of college? What if he isn’t ready?

“I don’t think I’m going to fail everything,” Carrington said. “But I think I’m going to be a bit behind.”

It’s a valid concern. Past valedictorians of low-performing District high schools say their own transitions to college were eye-opening and at times ego-shattering, filled with revelations that — despite taking their public schools’ most difficult classes and acing them — they were not equipped to excel at the nation’s top colleges.

When these students arrived on campuses filled with students from high-flying suburban public schools and posh privates, they found a world vastly different from the one they knew in their urban high schools.

For Sache Collier, it meant writing her first research paper. For Darryl Robinson, it meant realizing that professors expected original ideas, not just regurgitated facts. For Angelica Wardell, who grew up going to school almost exclusively with African American students, it meant taking classes with whites and Asians.

And for many top D.C. graduates, it meant discarding the idea that school is easy.

“You can’t make it in college by yourself,” said Wardell, who just finished her junior year at Ohio State University. “You need professors, you need friends, you just need all the help you can get.”

Wardell said she breezed through H.D. Woodson High before graduating in 2010 and heading to Ohio State, where the workload was immediately overwhelming. And the diversity was a social shock. But her lowest point came during sophomore year, when she failed trigonometry despite pouring herself into the course.

She had taken trigonometry in high school and earned a B.

“I basically thought I was stupid,” said Wardell, 21. “I just felt like, ‘What’s wrong with me? Maybe I’m not meant to be here at one of the best schools in the nation.’ I told my mom I wanted to leave.”

It was a temporary impulse, eventually drowned out by a chorus of encouragement from friends and professors. Wardell redoubled her efforts to reach out for help and earned a C-plus on her second try at college trig. She is majoring in public health and plans to continue for a master’s degree in the same field.

“I like to challenge myself, even though sometimes it frustrates me,” Wardell said.

College can be jarring for young people no matter where they’re from or how challenging a high school they attended. But experts and educators say the transition can be particularly difficult for first-generation collegians and students from struggling inner-city schools.

Nearly two-thirds of the District’s high school graduates enroll in college, according to the D.C. College Access Program, a nonprofit organization that offers college counseling and financial assistance to students in the city’s traditional and charter schools. (Washington Post Co. chief executive Donald E. Graham is the chairman of DC CAP’s board of directors.)

Of those D.C. students who enroll in college, 38 percent earn a degree within five years, compared with 54 percent nationwide, according to DC CAP. The Office of the State Superintendent of Education said that 37 percent of D.C. students who go to college complete a four-year degree in the six years after graduating from high school.

District schools officials said they are looking for ways to improve students’ high school experiences. The need for more rigorous academics was one reason the city adopted the national Common Core standards, which demand critical thinking and problem-solving from students starting at a young age, said Melissa Salmanowitz, a schools spokeswoman.

But motivated students said they can get lost in classrooms dominated by disruptive students or students who are years behind and struggling with the basics.

Collier, the 2011 valedictorian at Ballou Senior High in Southeast Washington, said the first thing she noticed when she arrived at Penn State University was how intently her fellow students paid attention during class.

“It was like, ‘Wow, everyone’s on the same page and everyone wants to learn,’ ” Collier said. “At Ballou, it wasn’t like that at all. I was always trying to get the students quiet.”

Collier had been a star at Ballou, where fewer than one-quarter of students are proficient in math and reading. But she said that her classes largely dealt with the basics: summarizing story plots, for example, and learning how to write complete and grammatically correct sentences.

Only in her senior year, in an advanced English course, did a teacher challenge her to think more deeply. “I feel like it was too late,” said Collier, who took two of the three AP classes she said were available to her at Ballou. “It just wasn’t enough to have that kind of teacher for one year.”

In her first semester at Penn State, Collier took seminars in which professors asked her to synthesize ideas, develop arguments and do original research. It was new to her.

“We had to go into the library all the time and research articles and really, really write,” Collier said. “It was difficult for me because I hadn’t done that in high school. I didn’t have to write a lot. I didn’t really research anything.”

The 2.1 grade-point average she earned that first semester devastated her. She visited writing tutors, talked to librarians and sought out professors during office hours. Now a rising junior, her GPA is 3.38.

“I’m not the type of person to give up,” Collier said.

Matthew Stuart, an AP English teacher at Dunbar, attributed students’ lack of college preparation in part to the city’s focus on annual standardized tests that demand little critical thinking or problem-solving. Many teachers give students simple strategies for tackling basic essay prompts, he said, but teachers don’t have a chance to venture into more difficult and stimulating intellectual terrain until after 10th grade, the final year of standardized testing.

“They’ll teach them coping mechanisms for essays, but they never teach argument,” Stuart said. “They never teach original ideas.”

Some D.C. neighborhood schools offer more rigorous courses that better prepare their students for higher education. Seth Brown took 11 AP classes on his way to becoming the 2010 valedictorian at Wilson High in Northwest Washington.

That meant he entered Dartmouth College with credit for at least five courses under his belt. Still, he was overwhelmed during his first semester at the New Hampshire Ivy League school because he was assigned two five-page writing assignments — longer than any assignments he’d completed in high school, he said.

“It was the most daunting task,” said Brown, a rising senior at Dartmouth. “I didn’t even know where to start.”

Students almost universally said writing is a significant challenge when they get to college. Darryl Robinson, a Georgetown student and 2011 graduate of Cesar Chavez, a D.C. charter school, said it was his first college writing assignment that taught him how much he had to learn.

Asked to analyze a memoir, Robinson wrote a simple plot summary. He hadn’t known how to develop an argument and back it up. His paper received a D-

minus, as he recalled in an opinion piece he wrote for The Washington Post last year.

“Other Georgetown freshmen from better schools had been trained to form original, concise thoughts within a breath, to focus less on remembering every piece of information,” Robinson wrote. “My former teachers simply did not push me to think past a basic level, to apply concepts, to move beyond memorizing facts and figures.”

Robinson went to Georgetown as part of the Community Scholars Program, meant to give low-income and first-generation college students the support they need to succeed at the elite school. He worked hard during that first year, he said, and now feels like he belongs.

Carrington, this year’s Dunbar valedictorian, is participating in the same Georgetown program. He plans to start school this summer, living on campus and taking two courses as he gets to know his new world.

A sports fan, he wants to major in business and someday serve as the general manager of the Washington Nationals, or maybe the Redskins. His teachers say they have no doubt that he has the patience, the fortitude and the smarts to make that happen.

They point to his commitment to playing second base for Dunbar’s baseball team, which was winless for three seasons until April, when Carrington hit a home run on the way to a victory.

“He’s extremely driven,” said his coach, Jeffery Anderson. “He has a plan for his life, and he knows what he wants to do.”

His mother, Valerie Carrington, still frets. “For the next four years, you have to do well,” she said to her son days before he graduated. “I’m going to be praying.”

Stuart, the AP English teacher, said that Johnathon Carrington will be playing catchup in college.

“As a teacher, you always wish you could have done more,” Stuart said.

In the valedictory speech to his Dunbar classmates Friday, Carrington acknowledged the challenges ahead.

“Our future will not come easy,” he said. “We achieved a great milestone in our life today, but it’s up to us to continue our road to excellence.”