Georgetown University (AP Photo/Jacquelyn Martin, File)

In two months, another crop of new high school graduates will head off to college. They will all depart the campuses at some point, but too many will leave without a degree.

Fewer than 40 percent of students enrolling for the first time at a four-year college actually graduate in four years. Even allowing an extra two years for financial challenges or new majors, fewer than two-thirds graduate within six years.

As the baby boomer generation leaves the workforce, the United States risks having successive generations less educated than the ones that preceded them for the first time unless we improve undergraduate education. Here are three ideas to get us started: 

Instead of focusing on tenure, focus on full-time faculty. We need to separate the debates about the future of tenure and its guarantee of lifetime employment from the growing use of part-time, adjunct faculty on campuses.

Only about one-third of college professors are tenured or on the pathway to tenure. That’s the statistic often used by faculty members who worry tenure is under threat as higher education leaders look to cut costs.

But focusing just on the tenure status of faculty is a mistake if we’re looking to cut college costs and improve undergraduate education. Not all faculty, whether tenured or not, are created equal in terms of costs. One recent study found that the increases in faculty salaries have been concentrated among large research universities and among a subset of academic departments.

“Within departments the highest-paid faculty teach fewer undergraduates and fewer undergraduate courses than their lower-paid colleagues,” wrote the study’s authors, Paul Courant of the University of Michigan and Sarah Turner of the University of Virginia.

Faculty salaries, they concluded, “are determined principally by research output and associated reputation.”

Indeed, there is a growing separation between faculty who teach and faculty who research at too many colleges, especially large research universities that enroll the largest number of undergraduate students.

Among those professors who mostly teach, too many are part-timers. Of the faculty members who are not on a track to earn tenure, almost half work part-time.

Full-time professors are more effective in the classroom and as mentors to students whether they have tenure or not, Jacques Berlinerblau, a professor at Georgetown University, noted in his new book, “Campus Confidential: How College Works, or Doesn’t, for Professors, Parents, and Students.” Berlinerblau maintains that the more prestigious the school, the less likely its most valued professors will engage with undergraduates.

On campus tours, prospective students and their parents rarely ask about faculty or how much time professors spend on research compared to teaching and advising undergraduates. Berlinerblau suggests families do their research by combing the college’s web pages to look at how many full-time professors your major’s department has and how many courses are taught by full-timers.

“The dreamier the school,” Berlinerblau writes, “the less likely it promotes a culture that emphasizes educating 18- to 24-year-olds. The less likely its distinguished faculty view teaching as the life’s calling that it surely is.”

In a recent column, I suggested that colleges adopt a recommendation from a former university president to put a cap on tenure—perhaps 30 years, followed by yearly contracts. The response from faculty was swift. The American Association of University Professors called it “a truly awful idea.” Others said that the cost of ever more administrators on campuses, not faculty members, is the real reason tuition prices keep rising.

Instead of fighting to get more professors on the tenure track, faculty advocates should focus on getting more full-time professors in classrooms, whether they have tenure or not.

Make the undergraduate degree more rigorous. One byproduct of the increased use of part-time adjuncts in college classrooms is that students have come to regard professors as yet another service provider. Adjuncts, hired by the semester, depend on positive student evaluations at the end of the term to get their contracts renewed. One way to ensure a good evaluation is to be an easy grader.

So the classroom has become one giant game of favor exchanges between students and professors. When they each play their parts, everyone comes out a winner. Students receive better grades and adjuncts keep their job year after year or spend less time dealing with complaints about bad grades.

A seminal study in 2011 that resulted in the book “Academically Adrift” found that one-third of college students made no gains in their writing, complex reasoning, or critical-thinking skills after four years of college. “American higher education is characterized by limited or no learning for a large proportion of students,” wrote authors Richard Arum and Josipa Roksa. For many undergraduates, they wrote, “drifting through college without a clear sense of purpose is readily apparent.”

The main reason for this, the researchers found, was a lack of rigor. Through surveys they learned that students spent about twelve hours a week studying on average, much of that time in groups. Most didn’t take courses that required them to read more than 40 pages a week or write more than 20 pages over an entire semester.

“You can’t assume that in sending off a student to a typical college that they’re going to get a rigorous education,” Arum later told me.

Design new pathways through the undergraduate degree. As the cost of college has spiraled upward, parents and students have focused more than ever on employment preparation and graduating on time. Intellectual discovery and exploration are no longer a priority, unfortunately. It’s too expensive.

To reduce the tension between the vocational training employers demand and the traditional liberal-arts education, the bachelor’s degree should be split into two parts: a one-year program of general education, followed by separate programs of varying lengths, depending on the needs of a given academic field. So after that first year, the credential for a computer-science major might take three years, but history or English majors might take just one, given that everyone is going to need further education throughout their lifetimes anyway.

The requirements for a bachelor’s degree already vary by major. What’s more, students are already patching together their own versions of a bachelor’s degree: one-third transfer to another college at least once before earning a diploma.

Concerns about the state of teaching led the Carnegie Corporation of New York in 2015 to fund the Commission on the Future of Undergraduate Education. The panel has started to issue studies from its work and its final report is expected next year. Its recommendations and the work some colleges are already undertaking to reform undergraduate education can’t come quickly enough.