College courses that don’t challenge students can hurt them. They need to go.

I confess I took a course in college — celestial navigation — that required no homework and included a boat trip around the local harbor as a final exam. We called such courses “guts.” The college classmate I have been living with for several decades says, “We treasured them when we found them.”

She is correct, but new findings from the National Survey of Student Engagement suggests this may be getting out of hand. Just 54 percent of first-year students and 61 percent of seniors said they were highly challenged by their courses.

NSSE (pronounced “Nessie”) is the largest and most respected measure of how undergraduates are learning and what they think of the process. The 2015 survey collected responses from 315,000 students at 585 four-year colleges and universities in the United States and Canada.

The survey’s authors say the lack of challenge in many college courses may stunt learning in a significant way. Students who said they were highly challenged by their courses “were more likely to engage in a variety of effective educational practices,” the survey said. Doing their best work meant strategies such as “active reading, reviewing notes after class and summarizing what was learned,” the survey said. Nearly half of surveyed four-year college undergraduates apparently don’t think they are being encouraged to do that.

We are not talking about party schools making the more prestigious campuses look bad. The extent to which students said they were challenged “was unrelated to admissions selectivity for first-year students,” the study said.

This is in part the result of U.S. colleges operating with almost no independent assessments of how well their students are learning. When the George W. Bush and Obama administrations suggested programs to gauge what was going on in college courses, college presidents erupted in outrage. The idea has since gone nowhere.

When I contributed to a collection of essays on this phenomenon a decade ago, University of Central Florida economist Mark Soskin told me that “it is convenient all around for students, faculty, taxpayers, legislators, alums and donors to pretend that high quality and relevant learning is going on. . . . Establishing standards or even publishing measured learning would reveal that the emperor, if not naked, has a much skimpier wardrobe than commonly presumed.”

The American Council of Trustees and Alumni has been at war for many years against pop courses that substitute for substantial learning. One Ivy League school allowed students to meet its math requirement with a course called “Reasoning About Luck.” Another Ivy campus gave humanities credit for “Ghosts, Demons and Monsters.” The council’s latest review of more than 1,100 institutions found that just 2 percent of them required at least six of the seven subjects it considers essential to a liberal arts education: literature, composition, economics, math, intermediate-level foreign language, science, and American government and history.