Stephen F. Petersen's business is growing, and he needs to grow with it.

But the thought of going back to the rah-rah atmosphere of a full-blown college to cope with schedules and scattered classes after a long time in the real world of business was not very appealing. Petersen opted for University of Phoenix, where he can upgrade his business skills on his own terms."This was best for me in terms of time and convenience. They offered the classes I needed so I could get that piece of paper on the wall. The University of Phoenix was a little more expensive, but the one-night-a-week format worked very well for me."

The university has been operating in Salt Lake City since 1984.

Petersen's classmates tend to be others who have backgrounds in business but are working toward additional credentials. Sharing experiences becomes a significant part of the university's advantage, he said, especially as classes are kept small.

"As students participate, we can draw on each others' experiences. This format fits very well with my personality," said Petersen. He also appreciates the fact that many of his instructors are currently working in the field in which they are teaching.

In his earlier college experiences, he said, he often encountered instructors "who had a good understanding of theory, but poor ability to help students apply what they were learning."

Robert C. Simmons, a University of Phoenix instructor, agrees that the university's philosophy makes students "partners in learning rather than passive recipients of information."

Simmons, who has experienced education from many directions, said the Phoenix program has objectives that are more clearly defined. The curriculum is more outcome-driven, he said, as students tend to come to the school with specific career goals in mind.

Because many of the students have broad experience in business, it is more challenging for the instructors. "I glory in the fact that each of my students is different," said Simmons. "Each takes away from here what is essential to himself."

Private educational institutions such as University of Phoenix meet a new need in education, Simmons said. "People today don't go to school and get a degree then leave never to return. There is more need for maintenance education opportunities."

Petersen's background is typical of U. of Phoenix students. He had a start-and-stop experience at the University of Utah, dropping out when two daughters had significant medical problems. He ultimately earned an associate degree in accounting at a business college and then became a CPA by successfully passing the exam without actually completing college courses - an option no longer available.

Today, his business is increasingly requiring him to deal with other states where his credentials may not be accepted, he said. He needs to meet the requirements of those states in which he has clients.

"I also need more information. A significant portion of my business is consulting on business issues. I've developed a good understanding over the years, but even a good consultant doesn't know everything."

Petersen has completed the work for a bachelor's degree and is about half way through a master's program. He has expedited his university experience, sometimes carrying a double classload. He started in January 1989 and expects to have his MBA in the fall of 1991.

Enrollment at the University of Phoenix indicates a growing demand for the educational opportunities offered there, said Craig Swenson, director. The August 1990 total of approximately 1,500 students was the greatest ever - an increase of about 300 students over the previous year.

The university is, in fact, outgrowing its quarters in a building off the 5300 South exit of I-15. Straining at the seams is "a pleasant problem to have," said Swenson, who is looking at several alternatives to house a growing number of courses and students. Opportunities for nurses and teachers to upgrade their credentials have been added recently. Extensive outreach programs also have been established in Orem and Ogden, and classes are taught in other locations as needed.

The Salt Lake campus is one of nine associated with the University of Phoenix family. More than 10,000 students are enrolled in the facilities.

The schools are based on the educational concepts of their founder, John Sperling, who saw a need for more opportunity for adults in a non-traditional setting.

Fees for an hour of undergraduate credit range from $145 to $176, while graduate courses top out at $188 per semester credit.

The instructional approach assumes that adults learn differently and have different needs from high school graduates going to college for the first time, Swenson said. The huge classes and lecture methods of the standard university are replaced by small groups and instructors who serve largely as facilitators.

Curriculum is centrally controlled and developed by faculty. Adult students become more responsible for their own education. Students move in cohort groups at their own pace.

Students at the university, which is accredited by the Commission on Institutions of Higher Education of the North Central Association of Colleges and Schools, are eligible for federal aid. Some of those already employed receive tuition reimbursement from their companies as a benefit.