There are telltale signs to show that these still are high school students: the T-shirts that say Coolidge High School or Gonzaga Eagles; the shyness about speaking in front of the class; the talk about senior class trips to King's Dominion and Disney World.

What makes these 319 high schoolers different is that they are also full-time freshmen at the University of the District of Columbia. They are part of Project Early Start, a special program set up in February to help those students 18 or older who would have lost their social security benefits this month unless they were attending college full time.

The college credit they earn in this program also counts as their final semester of high school work.

Despite the fact that these students had to make an abrupt adjustment to college life, and some were even failing certain of their high school classes, UDC officials say all but 40 are passing the college courses.

The youngsters, most of whom attended D.C. public schools, have done as well as the average UDC freshman, and some are getting better grades now than they did in high school.

The university environment, where students are referred to as Mr. and Miss, classes are smaller and the atmosphere quieter, seems to have agreed with many Project Early Start participants.

"Anacostia High School is kind of a noisy place. At lunchtime, if you wanted to study, you wouldn't be able to. You could go to the library, but they were constantly putting people out for being noisy," recalled Kenneth Blackwell, 19.

Blackwell says he can go now to the lounge in the old Miners College building at Georgia Avenue and Euclid Street, where the Project Early Start classes are held, and "get into some serious studying." He said he is doing 10 more hours of homework each week and that his grades have improved at UDC to Bs and Cs.

There have been adjustment problems for some. Phillip Robinson, 17, from Coolidge High in upper Northwest, said he has yet to get used to the fact that his professors do not collect homework. "That compels you not to do it. But if you don't do it at all, you'll mess up on the tests," Robinson said as he relaxed in shorts and T-shirt on the school steps between classes.

Robinson said his grades have declined somewhat.

Stefan Thomas, 19, another Coolidge student, said he had to get accustomed to more frequent testing. "They expect more out of you. The tests are very difficult. In high school, we would finish a chapter or two and then have a test on it . . . Here we have tests two times a week sometimes" in a single class, Thomas said.

"What I like about UDC is the ability to be more independent," said James Partee, 18, who came from McKinley High. Partee said his grades have improved from Cs to Bs because he has become more serious about his school work.

"I realized that I'm on my way to being on my own," he said. "In high school I was still relying on my friends and my teachers, now I rely on myself," he said.

Part of the impetus for students to do well stems from the fact that they will neither graduate from high school nor retain their social security benefits, which average about $259 a month, if they flunk out of Project Early Start. All of the students who receive these benefits come from homes where a parent is deceased, retired or disabled.

At mid-terms, 227 of the students had C and D grades (60-79); 49 had As and Bs (80-100); and 43 were doing failing work. Like the average UDC freshman, most of the Early Start students had to be enrolled in remedial math and English courses before moving on to college-level math and English.

"It's not bad as a bell-shaped curve," Mervene Couch, deputy vice president for academic affairs, said of the students' performance. "They are doing as well as the student body as a whole in their first year, first semester."

She said the professors teaching in Project Early Start were told to grade the high schoolers the same way they would their other freshman students, whose average age is about 23.

Only four students have dropped out of the program, she said.

Other area colleges, including Montgomery College, Prince George's Community College and George Mason University, also accepted high school students early as a result of the change in Social Security regulations, but UDC by far has the largest group.

Lisa Fisher, 18, of Eastern High, said she initially enrolled in Project Early Start to keep her social security benefits, but then became more interested in staying in the program because it will allow her to get a head start on college. To have more study time, she quit her job as a part-time clerk for the Defense Department, sacrificing $300 in additional monthly income.

"I feel as though getting an education will help me out more than working. My job at the Defense Department is not what I want to be doing in the future," she said.

"It was an awakening for me," said 18-year-old Ballou High student Priscilla Martin, from Anacostia. "In high school, your teachers would say, 'Do this, do that.' Here it's up to you to do your work, to keep pace. They don't talk to you like you're a little kid."

Although the majority of the students are expected to stay at UDC after this semester, some said they plan to transfer to such schools as Morgan State University in Baltimore, Harding University in Arkansas and Howard University here. Others said they planned to attend art or computer schools.

Several of the UDC professors said they found that many of the young students were not accustomed to writing essays and compositions. Both Charles Lund, who teaches college-level English, and Gregory Rigsby, who teaches remedial English, said many students tend to write in sentence fragments.

Jim Campbell, who teaches government, said he found some Project Early Start students better prepared for college than his other UDC students, but added that quite a number lacked "study skills, basic reading and writing skills" and had difficulty reading a government book on 10th or 11th grade level with comprehension.

"My guess is that the kids who do well come from professional families where their mommies and daddies have degrees and encourage them to read the newspaper and discuss public issues," Campbell said.

Spanish professor Jose Gil said he found that the students lacked a certain "mental discipline" initially. "Their attention spans are very short. I think this is because they have not been trained to deal with books. There are so many visual aids now in the schools." He added, however, that only one of his Spanish students is failing.

Several of the professors said the Project Early Start students exhibit an enthusiasm for learning they do not always see in their older students.

"In terms of their attitude, I am very, very impressed. It runs contrary to what I hear about the public schools," said Rigsby.