Some Montgomery County teachers are speaking out against a new guideline that makes 50 out of 100 the lowest possible grade for an assignment, even if a student hands in a blank piece of paper -- or no paper at all.

Normally, such work would rate a zero. Betsy Brown, director of curriculum development for the school system, said the guideline -- one element of a broader overhaul of the county's grading policy -- is designed to make sure grading increments are equal. Because an A is given for scores ranging from 90 to 100, a B for 80 to 89 and so on, it doesn't make sense for an E, or failing grade, to range from zero to 59, she said.

Jerry Link, a chemistry teacher at Northwest High School in Germantown, said giving a 50 can make sense instead of giving a zero. "If a kid was short with one assignment, that pulls his average down so much," Link said. "With a 50, at least he's back in the ballgame."

But as classes resumed last week in county schools, several other teachers said it seemed foolish to give the same grade to one student who shows she knows half the material and to another who exerts little or no effort. "The difference between doing nothing and getting half of the answers correct on a quiz or test means a lot in terms of mastery," said Julie Greenberg, a math teacher at Montgomery Blair High School in Silver Spring.

Five years ago, Greenberg called attention to the way county math exams were graded, with the scores needed to pass varying widely by school. Officials have said the issue she raised was one catalyst for the new grading policy, which is designed to ensure that grades are based solely on mastery of academic material and mean the same thing from one classroom to the next.

The school system has issued most of the guidelines in elementary and middle schools starting this year. Until the 2005-06 school year, many of the guidelines are intended to be only recommendations at the high school level, administrators said. Brown said high school leadership teams have been given leeway to decide which elements will be recommended this year and which will be required.

Greenberg said she finds it specious to argue that the E grade increment must be equal to the others. For one thing, she said, the increments don't mean the same thing: E means a student hasn't mastered slightly more than half the material, and the other grades represent marginal improvements beyond that.

Several other county teachers interviewed about the new guideline said they would comment only on the condition that they not be identified, fearing recrimination by school system officials. "It's almost impossible for a student to fail," one high school teacher said of the 50 percent guideline.

Marc Elrich, who teaches fifth grade at Rolling Terrace Elementary in Takoma Park, said the new approach loses specificity that could be helpful to parents, students and teachers. For example, he said, knowing that a student is getting C-minuses tells you more than knowing that he is getting C's. And it could change a final grade: "A kid could get a bunch of 89s and one 97 and his average is an A. . . . You really do lose some measure of fine tuning," Elrich said.

Math teachers often grade papers based on the percentage of questions answered correctly, and they worry that using five increments instead of the 100-point scale is not specific enough. "What they're trying to do with this policy might work for English, but it doesn't work for us," said Judith Higgins, a math teacher at Poolesville High School. "To my knowledge, I don't know any teacher who wanted this."

Another guideline that has drawn concern says that homework handed in after the due date can be penalized only one grade. (Until now, many teachers dropped one letter grade for each day late.) After a certain period, a missing assignment can be marked as a 50.

"A grade reflects achievement -- not deportment, not turning work in on time," Brown said. "If that was a masterful essay and the student happened to be three or four days late and so gets a D, that distorts the meaning of the grade."