To hear Irene Davis of Fairfax tell it, her husband John decided to leave the Navy because he tired of having his children change schools every time he changed posts.

So, when the Davises decided to settle in the Washington area, the couple spent more than a year looking at schools,on the theory that they would buy a home near one they liked.

The school they liked best was Robinson Secondary School in Fairfax County, a sprawling brick building that houses more than 4,000 seventh- through 12th-graders from the southwestern section of the county. They liked it, especially, because once their children were enrolled, they could stay through their junior high and high school years.

Today, the plans of the Davises and hundreds of parents like them are threatened. Crowding at Robinson, coupled with changing school populations, is forcing Fairfax County School Board members to consider recommendations to change Robinson's enrollment boundaries.

Under a proposal favored by School Superintendent William J. Burkholder, about 487 Robinson students -- including Patrick Davis, 13 -- would go to other schools starting next fall.

Burkholder has recommended that seventh-, eighth- and ninth-graders living west of Rte. 123 go to Lanier Intermediate or Fairfax High School. (Alternatively, Burkholder suggests converting Robinson into an eighth-through-12th-grade school, and sending the schools' seventh-graders to Frost or Lanier intermediate schools instead.)

This is not what Irene Davis anticipated when she so carefully shopped around, comparing SAT scores and teachers. She does not have specific complaints about the other schools, she says, it is just that Patrick is so happy at Robinson. "If a child has an environment that he feels comfortable in, you don't pull the rug out from underneath him," she said.

School boundary changes in a fast-growing county such as Fairfax are among the most emotion-packed issues for its residents. At stake, parents say, are neighborhoods, property values, and, most importantly, their children's futures.

Overall, the problem is that there are too many students in schools in the fast-growing western half of the county, and not enough in the more stable eastern half.

"Unfortunately, it's not a stable population," said Area IV Superintendant Arthur Gosling. "It's a growing and volatile population picture."

And, the only way to match students with school buildings, administrators say, is to readjust boundaries to alleviate overenrollment while new schools are being built, and to close others in areas where underenrollment is the problem.

"Everybody says 'Fine. You move your children, but don't touch my children,' " said School Board member Anthony Cardinale.

"People love their schools in this county. They don't like to change, and we understand that," said School Board Chairman Mary E. Collier. "But, we also must deal with a very dynamic population shift."

Changes at Robinson are among the many school boundary issues the School Board will consider at public hearings scheduled for Feb. 21, 23, 25 and 26. A vote on the boundary changes is expected March 14.

The Robinson plan is not the most drastic the School Board will consider at that time. It also will decide, for example, on whether to convert Groveton High in the southern part of the county to an intermediate school, dividing the school's 1,200 students between Fort Hunt and Mount Vernon High, and closing three intermediate feeder schools. But the Robinson plan is of great concern to those affected.

Robinson, located on Sideburn Road, has 4,610 students, or 560 more than it was built to hold. Unless something is done, school officials predict, the number of students will rise to 4,854 next year, 5,008 the following year and 5,094 the year afterward.

The county plans to build a new school at a Braddock Park site to absorb Robinson's overflow and accommodate new families moving into the southwestern section of the county. But, the $23 million school is not scheduled to open until 1988-89, and something must be done in the meantime, school officials say.

Last week, 500 Robinson supporters turned up at a public meeting to show their concern. "People say, 'Oh, if you parents would just step out of it, the kids would get adjusted. They don't care,' " said Mary Johnson, mother of a Robinson student. "But, they do care."

Jason Tenberg, 13, a seventh-grader, says his family moved to Fairfax earlier in the year from Texas. "I was just getting used to Robinson," he said.

Jennifer Gardner, 12, also in seventh grade, would not have to change schools. "But, half my friends in sixth, seventh and eighth grades will have to go to another school," she said. "I'll probably never see them again."