Several students at the Thomas Jefferson High School for Science and Technology in Fairfax County noticed their linear algebra teacher was struggling this semester. They said he made mistakes, erased his work without explanation and seemed confused.

Then it got worse. He quit in mid-March. The administration had to scramble. Retired math chair Jerry Berry, with no experience teaching linear algebra, kept an eye on student progress while a George Mason University graduate student provided the instruction. The graduate student look a leave when his wife had a baby. Another graduate student replaced him. A substitute teacher without much linear algebra experience replaced Berry as supervising teacher, telling students he would do his best.

This happens in regular schools, but Jefferson is the least regular school imaginable. It is our nation’s most selective high school, with an average SAT score of 2,218, serving a broad swath of Northern Virginia. It is known for its great faculty and splendid equipment. “Multiple teachers is not ideal, and almost unheard of at TJ,” said Myra Spoden, who teaches other linear algebra classes at the school.

“I have never seen it happen before,” said Jefferson junior Tahmina Achekzai, who has friends in the linear algebra class.

“Since spring break, we have had a teacher less than half (39 percent — I did the math) of the time,” a Jefferson student identified only as someone in the class wrote in an e-mail.

Some Jefferson students and faculty say I criticize the school too much. I don’t think that is the case here. Spoden, Berry and other math teachers did a great job in a crisis. Jefferson is a wonderful place to learn. But it is good for the millions of teachers, students and parents at schools not so blessed to know that even this superschool has no instant cure for teachers who stumble and quit unexpectedly.

Linear algebra is a college course above the level of calculus and almost never taught in high school. Jefferson and other Fairfax County schools are doing it anyway. Berry said the county and GMU have been in partnership for several years to train teachers so that any county student who wants to take linear algebra or multi-variable calculus can do so.

That does not mean that a trained linear algebra teacher can be found right away in March. Spoden called it “a challenge,” but one “I feel our administration has more than met.” The anonymous e-mailer who complained of the disruption acknowledged that Spoden “is a wonderful woman who genuinely cares about how the class is going.”

Spoden said she and other faculty members sacrificed their planning time and other needs to help with the class. “Linear algebra tutoring is available twice a week and on days it is not offered, linear algebra students have simply come to my calculus tutoring for help,” she said.

Students in the affected class were under the impression that they were scoring lower than other linear algebra students on the quizzes and tests that all take. Spoden said that is not so. “I have personally graded each and every assessment,” she said, “and I am confident they are fully grasping the material.”

Berry said: “I made sure that the students had the necessary resources which included class notes, exercises and review materials. If the students had questions about homework or review exercises I would provide help if I could and if not I would find someone who could.”

John Torre, spokesman for the Fairfax County public schools, said the system is doing what it can to make sure next year’s linear algebra instructor has all the necessary skills and experience. “All interested candidates should contact the principal, Evan Glazer,” Torre said.

The new person will need the self-confidence to deal with very demanding students and their parents. They should know that no school in America is immune to sudden reversals when teachers falter. The only remedy is the restoration of good teaching with lots of support.