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Today, three in four undergrads are considered "nontraditional" students.

The 18-year-old college freshman is an endangered species.

Today, three in four undergrads are considered "nontraditional" students. They may work while taking classes. They may have started families or served in the military. Or, as is often the case at my institution, the University of Utah, they may have done missionary work for as long as two years after high school.

The on-campus model doesn't work for this growing group of students. They can't raise families in dorms. And morning classes aren't compatible with full-time jobs.

Some new entrants to the college marketplace believe they can deliver an education entirely online. But the evidence suggests otherwise.

Colleges must forge a middle path between these two extremes. A blended model, combining online and on-campus education, may be the best way to ensure that students graduate on time — and on budget.

The number of full-time college students is dwindling. About 40 percent of students attend school part-time.

The ever-rising cost of tuition has made work necessary for many students. In the past 30 years, the cost of an undergraduate degree has increased over 250 percent.

According to a recent census report, over 70 percent of undergrads work. One in five of those students is at his or her job at least 35 hours per week. Of those that don't work full-time, more than half work over 20 hours a week.

But as students log more time on the job, they spend less time at school. So they're taking longer to graduate. Only 22 percent of part-time students at four-year schools graduate within six years. More than 67 percent of part-time students end up dropping out.

In other words, two-thirds of part-time students pay tuition for years — yet fail to emerge with a diploma.

A new crop of online colleges hopes to solve this problem by meeting nontraditional students where they are. After all, it's tough to "drop out" if going to college is as simple as logging onto the Internet.

About 1 million U.S. students opt for fully online education each year. Thirty-eight percent of them work full-time. Another fifth work part-time.

But online-only education hasn't boosted graduation rates. According to a study from the Education Trust, the graduation rate at some online-only schools runs as low as 5 percent.

Some traditional colleges are tiptoeing online by launching free MOOCs — Massive Open Online Courses. Anyone can enroll. In some cases, students can pay for a certificate that they've completed the course.

MOOCs were supposed to allow students anywhere to get an elite education and make paying for college a thing of the past.

But these courses aren't replacing on-campus instruction. They're supplementing it. Only 7 to 9 percent of students who sign up for a MOOC complete it. Eighty percent of enrollees in MOOCs offered by the University of Michigan and the University of Pennsylvania from 2012 to 2013 already had a degree.

So how can colleges effectively educate both traditional and nontraditional students? They must enhance their on-campus offerings with the tools an online approach affords.

To start, colleges could move lectures online and reserve campus time for small-group instruction. At the University of Utah, for instance, we're working to become a "hybrid university" by putting courses with high enrollment demand and those that are repeated often online. About 25 percent of our students take at least one class online, in conjunction with face-to-face coursework.

Such an approach allows on-campus students to tailor their course load to their learning style. And it grants them scheduling flexibility, which they may need if they're working.

Nontraditional students like veterans and parents, meanwhile, may find that a blended model provides access to high-quality classes and programs they might otherwise not be able to take advantage of.

Institutes of higher learning could also invest in programs that empower folks with some college to complete their degrees online. At Utah, we're launching programs in high-demand fields like business and nursing to do just that.

Most teachers prefer blended models. Ninety-three percent of college faculty consider meaningful instructor-student relationships necessary for a high-quality online course.

Evangelists for online education agree. As Piotr Mitros, chief scientist at edX — one of the largest providers of MOOCs — explains, "Closeness to teachers really does help student outcomes. … Machines are never going to replace the need for the human connection."

Blended-learning options can deliver the high-quality education that both traditional and nontraditional students need — on a timetable that works for their budget.

Ruth Watkins is the senior vice president for academic affairs at the University of Utah.