U.S. Education Secretary Terrel H. Bell, who has sent all four of his children to Fairfax public schools, praised the Fairfax County school system yesterday as "the best" in the Washington area and "one of the greatest" in the United States.

When his family first moved here from Utah in the early 1970s, Bell said his sons had to make "a mad scramble to get caught up" with their classes. More recently, he said, Fairfax's high standardized test scores were "an enormous accomplishment for such a large, complex system."

Bell made his remarks in a speech to about 700 Fairfax school administrators meeting at Mount Vernon High School. He also urged them to take the lead in using computers for teaching and in making sure both students and teachers were "computer literate."

Afterwards, Fairfax Superintendent William J. Burkholder said Bell's comments were "high praise from an official of that stature, especially since he was speaking from experience."

Burkholder said the Fairfax system already is using computers in its high schools and plans to introduce them next fall in junior highs. But he added: "I think limited resources will slow us down."

In his speech Bell made no mention of offering federal aid to help school systems use computers. He said he foresaw "an increasing budget pinch . . . until we get our economy going again and that may be a long time."

Bell told the school administrators that he first became familiar with the Fairfax schools when he lived in Reston in 1970 while he was deputy U.S. commissioner of education. He returned to his home state of Utah to become superintendent of Salt Lake City schools but then moved back to Reston in 1974 when he was named commissioner under President Ford.

When he became education secretary last year, only his youngest child was still of school age. The boy, Peter, 11, attends Tuckahoe Elementary in Arlington, where Bell now lives. The secretary said he was "impressed by that school" but he said still felt Fairfax is "the best school system in this area."

"I wonder if the people of Fairfax County appreciate the high quality," he added. Sometimes, he said, "it isn't recognized as much at home as it is around the country."

With 124,000 students the Fairfax system is the 10th largest in the United States. Last week the Virginia Education Department reported that Fairfax had the highest overall average scores in the state on standardized achievement tests.

Last year its high school seniors had the highest average scores in the Washington area on the Scholastic Aptitude Test (SAT), surpassing both Montgomery and Arlington counties for the first time.

Speaking of computers, Bell said, "the time is approaching very, very rapidly" when there will be "bookless schools and paperless newspapers," which will permit teachers to "optimize" learning for every child.

"The potential for teaching is enormous," he said, "because the computer has an interactive capability that can respond one-on-one to a youngster at the keyboard." All the tedious part of education--the drill and practice--can be handled by computers, he said, "freeing up the teacher for something else . . . dramatically increasing the teacher's productivity."

"Youngsters will be so much better educated and so much brighter," Bell declared. "They will have to be because of international competition."