Arkansas' controversial teacher competency test, failed by 10 percent of the state's educators, was a necessary though painful method of weeding out "incompetents," the head of the state's education reform committee told skeptical teachers yesterday.

Hillary Rodham Clinton, wife of Arkansas Gov. Bill Clinton, a key figure in developing the tests, also said the examinations are smart politics that will help voters accept the state's first sales-tax increase in 26 years.

The Arkansas test has become the lightning rod for opponents of teacher competency tests. It was the first such statewide test, preceding similar tests in Georgia and Texas. In Texas, scores of teachers' union volunteers are crisscrossing the state tutoring teachers to help them pass.

The National Education Association, which unsuccessfully fought the Arkansas test in court, announced at its convention here last week that it would wage similar court fights against the Georgia and Texas tests.

Clinton, a lawyer, ventured onto hostile turf -- an issues conference of the American Federation of Teachers. She said the Arkansas test, although "painful," was needed to weed out teachers who were "incompetent" and to restore public confidence.

The public perceives that many classroom teachers are incompetent, Clinton said, "and whether it was fair, whether it was accurate or true, we were going to have to come to terms with the perceptions that were there."

"The problem and the perception had to be dealt with together," she said. "The political reason . . . as well as the substantive reason has to be given."

Her appeal was followed by a rebuttal from an education researcher who said Arkansas ranks last among the states in teacher pay, and "you get what you pay for."

Ten percent of Arkansas' 28,000 teachers failed the test, with the largest proportion failing the writing part. That part required teachers to write 200-word essays on various themes, such as a letter to be sent home to a parent, or a letter to colleagues explaining a teaching innovation.

Clinton said the test was so simple that every teacher should have passed. "Nobody should have failed our test," she said. "The fact that 10 percent failed is very significant. Those 10 percent touch thousands and thousands of children's lives."

The delegates listened intently and applauded politely at the end of Clinton's talk. But the next speaker, education researcher Linda Darling-Hammond, was loudly cheered when she pointed out that Arkansas ranked 50th among the states in education spending, and that the average teacher salary in some Arkansas districts is $12,000.

"It is clearly true you get what you pay for in education," Hammond said.

Hammond, director of the Education and Human Resources Program for the Rand Corp. and author of numerous education reports, called Arkansas' test "a quick-fix political measure" which was "at worst, counterproductive."

The debate over teacher testing came on the final day of the AFT's annual "Quest" issues conference at the Sheraton.

The 600,000-member AFT and its rival, the 1.7 million-member National Education Association, oppose testing teachers who are already certified. But when the AFT conference opened this week, President Albert Shanker indicated that his opposition may be softening, as he told an interviewer that testing teachers "is not all an evil thing."

"If a person has been teaching for 20 years and they are illiterate," Shanker said in that interview, "then they ought not to be teaching."

While not quite an endorsement of competency tests for new teachers, his remarks were the most conciliatory to date on an issue that has seemed to seize the attention of the public, and of state legislators always anxious to appeal to popular sentiments.

Shanker said the NEA's highly vocal opposition to testing is hurting the profession.