For Daniel Gardner, 19, a junior at James Madison University in Harrisonburg, Va., the dread and dejection set in before classes even started.

Before resuming in-person instruction this fall, the university had laid out a comprehensive 34-page plan emphasizing the “public health and well-being of our students, faculty and staff.”

But when Mr. Gardner returned to campus to help run freshman orientation in late August, he saw students crowded around tables in the dining hall. He saw students stumbling home from off-campus parties. And he saw hundreds of students lounging around inches from each other, many maskless, during an outdoor movie night hosted by the university.

“It was kind of insane,” Mr. Gardner said. He remembered thinking, “this is not going to work if we move forward.”

Mr. Gardner’s musings proved salient. After only a week of in-person classes, this leafy campus in the Shenandoah Valley was overwhelmed with hundreds of coronavirus cases. The university shifted classes online, and gave students living in on-campus housing — many of whom were still settling in — six days to move out.

Students who had tested positive were told to continue isolating on campus; those who feared that they’d been exposed to the virus could petition the school to be allowed to remain longer than six days.

The university announced that this would be a “temporary transition,” with classes potentially resuming — and the possibility that students could move back to campus — as early as Oct. 5, if case numbers were low enough.

“We had classes for five days,” said Caitlyn Read, a J.M.U. spokeswoman. “In those five days, we saw some things that we need to address. We also saw some overwhelming victories in terms of getting 22,000 students in in-person instruction.”

“We planned for six months, but until you really see some of that stuff implemented, it’s hard to identify deficiencies,” she added.

In interviews, some J.M.U. students described the experience of watching hundreds of students around them test positive for Covid-19 as bizarre, chaotic and paranoia inducing.

The traditional autumnal return to campus — a time of reconnecting with old friends and diving headfirst into classes and activities — had taken on morbid overtones. Students spent their first week tracking campus case numbers, getting tested, reporting peers for partying, nervously getting meals at crowded dining halls and waiting for classes to be shut down.

Their experience is not unique. Thousands of students on campuses that have resumed in-person classes have watched anxiously as coronavirus case numbers have skyrocketed around them. As of Sept. 14, The New York Times counted more than 88,000 cases and 60 deaths at 1,190 campuses nationwide. (Not all of those cases are new, and the increase is partly the result of more schools beginning to report the results of increased coronavirus testing.)

At least eight schools have canceled in-person classes because of virus outbreaks, including the University of North Carolina at Chapel Hill; the University of Wisconsin, Madison; and Notre Dame. Others seem to be trying to power through the pandemic. The University of Alabama and the University of Georgia have continued to hold in-person classes despite more than a thousand positive cases of coronavirus at each school.

As case numbers tick up, students at these schools have been airing fears and concerns, and posting photos, videos and frantic questions, on Twitter, TikTok, Instagram and Reddit pages dedicated to their schools. There are also, of course, plenty of morbid jokes.

In a Reddit post on a J.M.U. page from Sept. 1, one person commented: “513 cases, only half of quarantine beds remaining as J.M.U. begins to resemble mid 1300s Europe.”

In another post, titled “We all need to work together Dukes!” (a nickname for J.M.U. students), someone wrote: “I know times are hard and classes just started, but 390 cases of Covid is absolutely pathetic. How are we going to let Alabama lead the country with 1,043!? We can catch up to them if we try hard enough, but it is going to take all of us!”

Arianna Mbunwe, 20, a junior at the University of Georgia, which reportedly had 2,600 cases as of Sept. 9, said: “We’re just resigned to the fact that we’re just going to eventually get it.”

“It shouldn’t be that way,” she added. “But there’s almost nothing we can do at this point.”

‘A Number of Isolated Incidents’

Like many other schools, the J.M.U. administration has placed the onus of responsibility not to spread the virus on students, asking them to sign a pledge that they would not gather in groups larger than 10.

The pledge listed at least nine specific requirements that students must “acknowledge and abide by,” including: “I will practice recommended physical distancing between others and myself” and “I will wear a face mask which covers the nose and mouth at all times when indoors in classrooms, labs and other public settings and outdoors when in the presence of others.”

The college has urged students not to attend parties, and has threatened those who did with consequences including suspension and expulsion. (The administration is currently investigating 232 pending violations, Ms. Read, the spokeswoman, said.)

Ryan Ritter, 19, a sophomore, summed up official J.M.U. messaging as: “‘The semester is in your hands. If the student body does not, you know, party or engage in any activity as dangerous, then we’re going to be fine.’”

But the movie night set a different tone. “This was incompetence from the university in dealing with this virus,” Mr. Ritter said.

It was the first in a series of four screenings that the university held as part of its official orientation program for freshmen. Mr. Ritter shared with The Times a screen shot of a school listing for the event, which encouraged students to “bring a blanket or towel to sit on” but made no mention of social distancing or masks.

In a photo Mr. Ritter posted on Twitter, groups of students can be seen sitting on the grass in close quarters in front of a large screen, watching the 2019 murder mystery romp “Knives Out.”

Mr. Ritter said he stayed for about 30 or 40 minutes, during which, he said, “half the people weren’t wearing masks.”

“The university left it on our student leaders to police it and go around and tell students, ‘Hey, put on your masks,’” he said.

Mr. Ritter said he felt that the movie nights set a precedent, that it made it seem OK for students to gather en masse outdoors.

“Students show up and they see these huge events and they start thinking, ‘Well, you know, the university doesn’t care. Why should I care? Why should I limit myself to these 10-person interactions?’” he said.

Ms. Read, the J.M.U. spokeswoman, said the movie night was “an attempt to create some sense of normalcy.”

“It was hosted outside in a massive field where students had every opportunity to social distance and still enjoy the programming,” she added. “Now, if students chose not to socially distance in an outdoor venue where that was possible, that’s probably not a great choice, but they absolutely had the option to.”

Students at other colleges have flooded social media with photos of outdoor gatherings and of their crowded classrooms and dining halls, expressing outrage at their administrations. On a Reddit page for University of Georgia students, people have posted memes mocking the university’s president, Jere Morehead, for keeping the school open even as cases have skyrocketed; others have uploaded footage of packed frat parties, demanding that the administration take action.

Gregory Trevor, a spokesman for the University of Georgia, wrote in an email that while “preventive measures we have taken on campus are working,” Covid-19 has spread at off-campus parties and local bars. “Where we have evidence and jurisdiction, we are moving aggressively against violators,” he wrote, adding that the university recently suspended a fraternity.

On Twitter, an account calling itself University of Misery compiles student complaints about poor conditions in quarantine dorms at the University of Missouri. (In an email, a spokesman for the university said that the administration had “reviewed our procedures and were able to make some adjustments” in response to the issues raised by the account.)

One video posted on Twitter showed more students in a J.M.U. classroom than there were seats available. Chairs had been taped over to encourage distancing, but the result was that groups of students just sat on the floor.

Gemma Dobbs, 20, a J.M.U. theater major who tweeted about her frustration with the university’s haphazard social distancing policies, described the feeling of walking into a crowded music lecture as “apocalyptic.”

“They’re putting all this pressure on us to not party and, and my friends and I aren’t,” she said in a phone interview. “And then all of a sudden, I’m in a room with 199 other undergrads, most of whom probably live on campus, and we’re sharing our germs with each other.”

“No part of it felt safe,” she said.

Ms. Read, the spokeswoman, said, “We have seen that content, it is troublesome. Those are the kind of things we’re going to address in the four weeks that we go online.”

On Aug. 26, the first day of class, the university reported 11 cases on campus. In an Aug. 28 email welcoming students to school, with the subject line “Cautious Optimism,” the president, Jonathan Alger, acknowledged “a rise in positive cases among the student body,” but said that the numbers would not immediately cause the school to change course.

“Interpreting epidemiologic data is so nuanced and dynamic,” he wrote. “In any given day, the number of new positive cases is not a singularly determinant factor in our decision making, even though that is often the focus in media and social media reports.”

That day, the school’s Covid-19 tracker hit 159 cases, provoking feelings of “impending doom,” Mr. Gardner said.

Students began criticizing the email on social media. One person posted a photo on Reddit of a banner hanging from an apartment building with the president’s email’s subject line “cAuTiOuS OpTiMiSm” — the mixed case capitalization used to indicate mockery — next to an image of Mr. Alger wearing a mask.

On Sept 1, the administration sent out another email, announcing a “temporary transition” to online classes. Students were given until Sept. 7 to clear out of their dorms. Many feared returning home to their parents would potentially spread the virus; the university said it would grant limited exemptions to students who feared infecting their family. Several students who lived off-campus said they did not plan to leave their apartments.

“There’s a number of things that are going to have to change between now and October 5,” said Ms. Read, referring to the planned reopening date for in-person classes. She acknowledged that there were a “number of isolated incidences that happened outside of the plan that we’re going to work to rectify.”

“Chiefly, we’ve got to get these numbers down,” she said.

Survival Tactics

Not all schools with spiking cases of the novel coronavirus have pulled the plug. The University of Kentucky lists 383 active cases as of Sept. 14 on its website dashboard, but the administration is holding firm and continuing to hold in-person classes. “Our strategy is evolving consistent with the operational playbook we began to implement in June,” Jay Blanton, a spokesman for the university, wrote in an email.

He said the university is also beginning wastewater testing: Sensors installed in pipes will analyze sewage for signs of the coronavirus, a technique that has been used on other campuses to help detect outbreaks before they happen.

“We began the wastewater testing last week, first examining one of our isolation facilities as a control group” Robert DiPaola, the dean of the University of Kentucky College of Medicine, wrote in a Sept. 4 statement provided by a university spokesman. “We have now moved to other residence halls.”

The sensors will be activated at times when sewage systems will be experiencing high usage from students, like the mornings.

Colleges and universities are using other tactics to track and contain the virus including tough social-distancing rules (sometimes enforced by R.A.s and other students) and an array of new technologies, including virus tracking apps. (Students who test positive for the virus are being sequestered in isolated dorms, hotels and apartments.)

Students who violate school policies face suspension, and worse; at Northeastern University, a group of 11 students who were found together in a room were expelled, and the school kept their tuition.

But college administrations can’t assume control for each individual’s every action.

“People won’t stop having parties people, won’t stop not wearing masks,” Ms. Mbunwe, of the University of Georgia, said. “The only thing I can really do is beg and plead with my peers to do the right thing. But even then, it’s like, when does our administration step in and decide to actually make real decisions regarding the health of their students?”