Standardized testing used to be a straightforward affair in Maryland. Once a year, students brought home carbon-copy sheets filled with percentile scores that compared them with children from Maine to California on a scale of 1 to 99 against a national average of 50.

These days, the percentile has fallen from favor.

How students stack up against the national average -- the standard measured by the Stanford Achievement Test, the Iowa Test of Basic Skills and other norm-referenced tests -- is no longer the chief concern of teachers, principals and superintendents in the Maryland suburbs.

Maryland, like Virginia and most other states, has embraced its own test and a new way of rating the performance of test takers. The two-year-old Maryland School Assessment (MSA) judges whether students have mastered material taught at their grade level. Parents are urged to focus less on scores and more on three broad categories of achievement: basic, proficient and advanced.

Education leaders say the new rating system tells parents more than any percentile could about whether students are performing at their grade level and mastering academic standards set by the state. How those students rank against their peers around the nation is a secondary concern.

"The standardized tests are important, but they tell you ultimately far less about your kid than what the teacher can tell you from the classroom," said Ronald A. Peiffer, Maryland's deputy superintendent for academic policy.

The percentile has not completely disappeared from the student testing universe.

The Maryland State Department of Education still dispenses percentile scores for individual students as part of its MSA reports to parents. It can do that because the statewide test was built from a core of questions taken from two venerable percentile tests. The Stanford Achievement Test, published by Harcourt, provides reading questions; TerraNova, from McGraw-Hill, supplies math content.

Parents say they appreciate seeing the familiar two-digit scores on MSA reports.

"It's just helpful to give you an idea of where your child stands," said Stephanie Coakley, a Howard County parent.

Coakley said parents may find it more meaningful that a child ranks at the 90th percentile, terminology familiar from their own childhoods, than to know that he or she rates "advanced" on the MSA.

"Percentiles, we all understand," said Sara Seifter, another Howard parent.

Peiffer notes, however, that he is hearing from an increasing number of parents that the percentile scores "are of less interest to them" because they have grown comfortable with the language of the MSA.

For many years before the era of custom-designed state tests, Maryland mandated that norm-referenced percentile tests be given statewide. Over the decades, the tests included the Iowa Test of Basic Skills, the California Achievement Test and the Comprehensive Test of Basic Skills (CTBS).

That era ended in 1991 with the introduction of the Maryland School Performance Assessment Program (MSPAP). Maryland resumed norm-referenced testing a few years later, Peiffer said, because the state school board "became uncomfortable with not having a national test to which we could compare Maryland students." The CTBS became that test, mandated across the state until the introduction of the MSA in 2003.

The shift away from percentile scores coincided with No Child Left Behind, a federal mandate, which established student proficiency as the goal of testing.

Around Maryland, most school systems abruptly scaled back their norm-referenced testing so as not to duplicate the efforts of the MSA.

Individual school systems continue to purchase and administer norm-referenced tests on their own, albeit on a much smaller scale than in years past. Montgomery uses the CTBS, Howard the TerraNova and Anne Arundel, Calvert and Frederick the Stanford -- but only for second-graders, and with less fanfare than for the annual ritual of statewide testing.

Some Maryland counties, including Charles and St. Mary's, give no norm-referenced tests, although St. Mary's plans to reinstate the Stanford test for second-graders this academic year.

Scores supplied to The Post by the Anne Arundel, Frederick, Howard and Montgomery school systems indicate students are performing above the national average in all four counties -- and substantially higher in Howard and Montgomery. Calvert and Prince George's declined to supply scores on the basis that they are used only for in-house diagnostic purposes. In Anne Arundel, Howard and Montgomery, parents can find and compare second-grade percentile scores for individual schools online.

Norm-referenced tests serve several purposes. They provide parents a rare perspective on how the local school system compares with those in the rest of the nation. They provide teachers data on individual student abilities at an age when instructors have little to go by; the MSA doesn't test students below the third grade. In some cases, percentile scores help schools identify gifted students.

Academic leaders caution strongly against inferring too much from the scores. While some tests, particularly those that form the core of the MSA, align closely to what's taught in the Maryland classroom, others do not. Each test has its own content and design. The tests tend to offer a grab bag of material drawn from several different states -- usually large states, to attract more customers -- and they may confront Maryland students with material those students haven't yet learned.

There is a contrary argument: that norm-referenced tests are valuable precisely because they come from outside the state testing apparatus. To parents who fear that teachers are teaching only what's tested on the MSA, and that students are getting a comparatively shallow education as a result, such a test could provide an independent measure of whether the lesson plan is sound.

While some academic leaders see little meaning in norm-referenced tests, others say the tests provide a valuable reference point for how students rate against their peers.

Montgomery Superintendent Jerry D. Weast "likes to be able to compare our kids' performance to kids around the country," said Brian Edwards, spokesman for the county school system.

But in Calvert County, Ted R. Haynie, the director of system performance, said there's little interest in such comparisons.

"We truly believe," Haynie said, "that focusing on the progress and learning needs of individual students and subgroups of students is more educationally prudent than comparing how our students performed on a national norm to students in North Dakota. Nothing against North Dakota."