The Washington school system has reported that substantial by fewer teachers are being reassigned after the start of the school year, this year as a result of major changes last fall in Judge J. Skelly Wright's school equalization decree.

A total of 31 elementary teachers have been switched to different schools since September to comply with the revised decree, including 16 who began their new assignments last week at the start of the spring term.

Last year, when Wright's original decree was still in force, 137 teachers were shifted in late November.

"The new decree is a lot easier to live with than the old one," said deputy Washington school superintendent Edward G. Winer, whose office is in charge of computing the reassignments. "The math involved is a lot simpler. The disruption is a lot less."

"This is the fair way to do it. It really is," said D.C School Supt. Vincent E. Reed. "This way we're sure every child gets a fair break."

Under the 1971 equalization decree, issued in a case brought by the late Julius Hobson, per pupil spending on teacher's salaries had to be within 5 per cent of the citywide average at every one of the District's 124 elementary schools. In the six years that the system operated under the decree about 675 teachers were switched to different schools several months after the start of fall classes.

The new order, signed by Wrighton Sept. 19, eliminates salaries as a factor in the equalization arithmetic. Instead, the pupil-teacher ratio at every elementary school must be within 5 per cent of the citywide average, insuring that all students have about equali-sized classes.

Wright, who sits on the U.S. Circuit Court of Appeals, has handled the case on special assignment as a U.S. District Court trial judge.

He signed the new order following a motion by the school board to vacate the old decree. The board had argued that the equal-spending requirement had led to wide differences in school programs because teachers' salaries vary widely (as much as 70 percent) depending on seniority.