The College Board has announced that its most important product, the Advanced Placement exam, will be administered as a 45-minute online test this spring, compared with the usual three-hour, in-person affair. This seemed a trifle to me at first, hardly worth the trouble, until I saw how the decision relieves a nightmare facing America’s colleges.

Advanced Placement has a powerful effect on U.S. high school curriculums by offering a chance for college credit if a student does well on an AP exam. That’s nice, but what of the much larger number of students already in college taking similar courses that have also been interrupted by the spread of the novel coronavirus?

The College Board could have told high schoolers the problem was too big to fix. No college credit this year. A college can’t say that to its students. They have paid thousands of dollars for those courses. If they don’t get credit, many old and flammable buildings on our most scenic campuses could go up in flames. At the very least, college deans would drown in livid calls and emails from parents who pay the tuition bills.

The AP decision suggests the solution for those endangered institutions of higher learning. Their students can get credit for the work they have done even if the semester ends in an incomplete mess. They might take digital exams, or maybe just one last essay assignment delivered by email. Their professors can give them credit with a relatively clear conscience, and then get back to washing their hands and hunting for toilet paper.

The announcement of a truncated AP test brought joy to many universities. It improved the chances they too could survive this crisis. One official at a very selective college, in a private note, thanked AP for its “incredibly kind and compassionate action.” International Baccalaureate, with a similar but smaller program, canceled all of its 2020 exams worldwide.

The College Board’s research before its decision revealed an obsessive need for those exams among high school students, despite their frequent complaints about AP stress. A survey of 18,000 AP enrollees found 91 percent wanted the tests. The number of exams this year will likely fall far below last year’s record 5,098,815, but the program should retain student and teacher loyalty.

All questions on the shortened AP exam will be free response, requiring thought and analysis. No multiple-choice questions. The College Board is spending significant money on anti-plagiarism programs to check millions of exam pages.

“While our solution is not perfect,” said Trevor Packer, College Board senior vice president for Advanced Placement and instruction, “I see no other path to fairness. If we choose not to cancel, we must test at home, since many will never be able to reenter a school building this year. This means digital testing and digital scoring and test questions that measure skills that cannot be derived by students’ having Internet access and access to chat rooms and phone calls and textbooks. We must do right by all the students who have been studying with such faith and commitment. But it will really be okay if we never have to do something like this again for a very long time.” He said he is focusing on getting low-income AP students linked up at home.

The exam is what gives power to AP and similar college-level programs like International Baccalaureate and Cambridge. No other high school courses have finals written and graded by outside experts. Your classroom teacher might like you, but she has no power to inflate your exam grade because you were so sweet.

Students embrace the legitimacy. In 900 pages of comments accompanying responses to the AP survey, they bemoaned the magic moments they are missing this year: big games, proms, senior trips, graduation ceremonies. They begged to be allowed at least one championship bout with an AP test.

College Board psychometricians say a good grade on an 45-minute exam, even though it will cover only the first seven months of the course, will show sufficient mastery for college credit. Packer revealed an AP secret: “In many ways, the value of the longer exam is to encourage teachers and students to cover the full scope of a course — not because we need all of those questions for the predictive validity of the exam.”

Sadly for the college professors and veteran AP teachers who grade the exams, they will have to do it all alone at home this year. Next year they should be able to return to traditional reading sessions at big hotels, full of camaraderie, humor and hard work. They often wear relevant T-shirts, like “Don’t drink and derive” for the math teachers.

Students in high school and college will know that they at least got something out of this catastrophe. They can start the new school year fresh, and hope for better.