“I really liked your party last night.”

Will Heffernan, an 18-year-old freshman, said the line through his University of Maryland-branded face mask, his words muffled by the cotton fabric covering his mouth. He stood before about a dozen other students, also masked.

“Say it again?” professor Sue Sherburne asked. She, too, was masked but spoke through a microphone to compensate for her muffled speech.

It was just an exercise, of course. Parties on and around the College Park campus have been outlawed. But Sherburne asked her students in the public speaking class to recite the phrase in different tones, fluctuating inflections and varying speeds to show how small differences in delivery can alter a message.

Heffernan’s emphasis on the word “really” made his message sound sincere, his classmates concluded. But to get that point across, Heffernan had to maneuver a face mask, maintain six feet of space from his audience and speak above a humming humidifier in the back of the classroom.

Welcome to college life during a pandemic.

“It was definitely difficult because I feel like I have to speak up a lot more to be heard,” Heffernan, who is studying physics, said after the Tuesday night class. “I feel like I have to exaggerate my facial features.”

After a chaotic spring, uncertain summer and a rocky start to the fall semester, universities in the D.C. area have found varying levels of stability. American, George Washington, Georgetown and Howard universities — which abandoned plans to conduct the semester in-person and opted instead to host most ­classes online — have reported a handful of novel coronavirus ­cases on and around their campuses.

At U-Md., a combination of wide-scale testing and the decision to delay in-person classes for the first two weeks of the semester have kept the campus relatively safe, said the school’s president. A phased reopening helped Catholic University control the virus, and George Mason University’s aggressive testing protocol has kept the caseload on the large campus in the double-digits.

“There is no silver bullet. You’ve got to do a lot of different things and you’ve got to do all those things relatively well,” said GMU President Gregory Washington. “Pretesting was a good move for us. The robotic delivery of food was a good move for us.”

Boxy, white, autonomous robots that deliver food from on-campus restaurants to students spread across campus had been a fixture even before the pandemic. Now Washington said he’d be surprised if the machines deliver fewer than 1,000 meals daily.

George Mason, whose 51,000 students and employees make it the largest public research university in Virginia, has conducted more than 7,200 tests for students since mid-August and reported 45 positives, university data shows. Out of 765 employees tested at the school, 15 have been positive.

The school in Fairfax County braced for a surge of cases during a recent round of testing meant to determine whether Labor Day weekend had introduced new cases to campus. But out of 2,400 tests on residential students, just 11 students contracted the virus.

George Mason officials hope to test 900 of the roughly 14,000 people on campus each week, including residential students, commuter students and employees, said Michael Sandler, a spokesman for the university.

“The idea with that is that if [the virus is] prevalent in a random sample, then you know you’ve got it on your campus somewhere,” Washington said.

Testing has also been a key piece of the reopening plan at U-Md., where officials used the delayed start of in-person classes to conduct campuswide screening. The university administered 20,000 tests over “a 15- to 21-day period” and reported 212 positives, President Darryll J. Pines told state lawmakers Sept. 16.

The success of testing encouraged Pines to resume face-to-face instruction Sept. 14.

“It’s good because you have in-person contact with people,” Alexa Polinsky, a U-Md. freshman from Scarsdale, N.Y., said after Sherburne’s public speaking class. “But you have to be cautious.”

Buckets of cleaning wipes sit outside classrooms for students to disinfect their seats before and after class. In Sherburne’s classroom, every fourth seat was open for a student. The rest were blocked with yellow tape.

“I feel they’re very compliant,” Sherburne said. She prefers teaching in person because there’s value in interpersonal connections. “I’ve been pleased with their willingness to follow the rules.”

But reopening campus hasn’t come without challenges. More than 200 U-Md. students were told not to attend face-to-face classes, report to in-person jobs or visit their friends after 23 students in their residence hall contracted the coronavirus. ­Thirty-five student-athletes tested positive for the virus earlier this month as the athletics department announced the resumption of Big Ten football.

The virus continues to spread on the campus. More than 6,500 tests administered between Sept. 20 and Sept. 26 produced 73 positive results, according to the most recent data available. An additional 87 students and employees who were tested off campus reported contracting the virus during the same week.

More than 60 percent of quarantine housing is in use, and the university is preparing three additional empty dorms to house sick students in case more beds are needed.

“Obviously, you know, we don’t want anybody to get the virus, but that’s impossible,” Pines told members of the U-Md. student government at a virtual meeting on Wednesday. “But our numbers are fairly low when you compare us to any university of our size, public, in the Big Ten [Conference].”

The climbing caseloads have raised fears among essential workers on campus, including housekeepers, facilities staff and bus drivers. Their union has clamored for more protective equipment and mandatory testing.

Members recently protested on campus and called on administrators to negotiate new safety standards. Crystal Foy, a 29-year-old housekeeper, said she worries daily about contracting the virus while cleaning surfaces in two academic buildings.

On Thursday, the union distributed 3,000 KN-95 masks to workers “due to the administration’s continued failure to protect staff working on campus,” leaders said.

At Catholic University, the sole university in the District with more than 5,000 students to invite students back to campus, about 570 first-year students spent their first two weeks in virtual classes and confined to campus. The measure “really helped a lot,” said Judi Biggs Garbuio, vice president of student affairs.

After the school administered 581 tests, 15 students living on campus were found to have contracted the coronavirus, university data shows. An additional 35 students living off campus have tested positive since the beginning of the school year.

Satisfied with the results, university officials lifted restrictions in early September and resumed in-person instruction. Then, the fitness center reopened and off-campus students were invited back to the grounds. Next came small in-person gatherings and the introduction of surveillance testing for athletes.

“Catholic University is really known for their sense of community and I think that really is a driving force” in the low caseload, Biggs Garbuio said. “They know it’s a privilege. It’s a community coming together to keep it open.”

Meanwhile, more than 70,000 students at American, George Washington, Georgetown and Howard universities are taking their classes online this fall. But the schools are still logging cases of the virus from employees, small groups of residential students and clusters who live off campus.

At AU, 20 students and employees have contracted the virus since Aug. 24, data shows. GWU has administered nearly 12,000 tests and reported just 13 cases.

Thirty-seven students and employees on or near Georgetown’s campus have gotten the coronavirus since Aug. 24, according to the school’s dashboard. Howard has overseen more than 2,100 tests, and nine students and faculty members have tested positive.

Georgetown and George Washington have the largest on-campus populations, with about 500 students each. AU has the smallest: 29. Howard is housing 144 students.

Despite the measured approaches schools have taken to reopen, leaders know circumstances can change overnight. They’re celebrating the successes — low positivity rates and compliant students — but also considering what could happen if their carefully engineered plans collapse.

“Mason’s covid rate is low, let’s keep it that way,” Washington, the George Mason president, warned students in an email. He reminded students to avoid large gatherings, wash their hands often and participate in random surveillance testing. “This situation can change rapidly, so we need everyone to double down on efforts.”