As a lawyer, Dennis Weldon has to make sense of tortuous legal papers. But a year ago, the Plumstead Township resident opened a nine-page document that left him flummoxed.

It was his child's report card from Gayman Elementary School in the Central Bucks School District.

Gone was the traditional A-B-C-D-F report from the teacher. Instead, parents were sent to their computers to click open a nine-page digital document with row after row of learning standards and success indicators for specific reading or math skills. Grades ranged from a high of E (exceeding standards), through M (meeting standards) and A (approaching standards), down to LP (limited progress).

Weldon said his wife, also a lawyer, struggled to comprehend the new "standards-based" report card, too. Another Central Bucks parent, a lawyer as well, told Weldon: "I don't even open it. . . . It's information overload."

The district has posted a 10-page handbook and seven videos on its website on how to interpret the evaluations, introduced in 2014 and used only in the elementary schools.

Many parents give the leading-edge system an F in the most important subject: telling them how their children are doing.

The largest suburban school district in Pennsylvania, with 20,000 students, Central Bucks has been struggling to successfully join the nationwide revolution in the way teachers assess their charges. The complaints of parents such as Weldon - elected to the school board last fall - point up some of the pitfalls in remaking an education icon.

Spurred on by national guidelines set out in the Common Core State Standards for English language arts and math, scores of districts across Pennsylvania and New Jersey have moved in recent years to ditch the old-school report cards that graded students competitively against their classmates, based on tests and quizzes. Replacing them: a puzzle of scores - numbers in some districts, letters in others - that judge the individual child's progress toward fixed goals, such as solving a particular math problem or completing a reading list.

Education experts say standards-based grading is far better at holding schools accountable for what students learn, especially when "grade inflation" has rendered A-B-C grades less meaningful. Said Rick Wormeli, a teacher, education consultant, and author of Fair Isn't Always Equal: "I should be able to go into any class and say, 'What are you supposed to be learning and where are you in relation to that goal?' "

David Bolton, assistant superintendent for elementary education in Central Bucks, said the changes were developed over two years by teachers, administrators, and consultants.

"They said our curriculum is completely standards-based, our instruction is standards-based, we ought to be reporting to parents and students on those standards," Bolton said. For instance, "instead of saying in math your child has a B, standards-based says, 'Here are the eight things your child is working on in this marking period and here's how your child is doing.' "

Along with arguing that the new report cards are what internet users might call "tl; dr" - "too long; didn't read" - many Central Bucks parents say they worry that the grading system rewards mediocrity by lumping too many students in the middle, as M's, and takes up too much teacher time.

"It works equally horribly for the student who wants to do better and the student who doesn't want to try too hard," said Dana Hunter of Doylestown, who sends two of her three children to Cold Spring Elementary. "I've had kids say: 'This is great. It doesn't matter how many I get wrong, I just get an M on everything.' "

Her kids agree. "They're too vague," said Sam, 8, a third grader who doesn't like to ace his tests and get an M while his lower-achieving classmates also get M's.

Parental angst over the new report cards helped a reform slate take over the Central Bucks school board last fall. The newcomers clashed with then-Superintendent David Weitzel over parent input. He left this month.

In the program's second year, district officials have shortened the reports from nine pages to six - still twice the length of the former report cards - and added a new higher-evaluation level for students judged to be doing better than simply meeting expectations.

Many schools, locally and across the nation, already have moved to some form of standards-based report cards - and often with not as much controversy as has occurred in Central Bucks, though parents elsewhere have also pushed back against the new system.

Haddonfield schools began using a standards-based report card system three years ago in kindergarten and have introduced it in an additional grade each year, to ease parents into the program. The lower grades, however, never received A's, B's, and C's - only fourth grade and up. Getting parents of those older children to accept the change "will be more of a focused effort," said Craig Ogelby, director of curriculum and instruction.

Thomas Guskey, a professor of education psychology at the University of Kentucky and a report card expert, said the changeover had been greeted enthusiastically in his state. However, he acknowledged that problems have occurred in districts, such as Central Bucks, when the new marks are too vague. "The middle category is too broad, the top category ill-defined - it's a classic mistake," he said.

In the North Penn School District in Montgomery County, officials rolled out a standards-based grading system for grades 3 through 6 last fall. They managed to keep the report card - which uses "exceeding," "meeting," "approaching," and "beginning" expectations in math - all on one page.

Elizabeth Santoro, North Penn's director of elementary education, said parents' main concern is how their children can earn an E. For the district, that means providing "opportunities for a student to say: 'I really nailed those standards. How do I go above that?' "

Jon Cohan, a Central Bucks father of two Cold Spring students, noted that when a wide range of students get an M, parents can't tell how their kids are doing.

"It's not that I'm demanding E's," he said. "I just want to know where she's good and where she needs help. They think you're demanding good grades. No."

Critics also say that the new grading system is an unpopular burden for teachers, who are reluctant to complain publicly.

"At the end of the day, I don't feel like it's worth the time the teachers are putting into it," said Cheryl Giacomelli, a Central Bucks parent and adjunct professor of psychology at Bucks County Community College. She said the new report cards don't give her any more information about how well her children are doing.

Bolton said the district was crafting improvements and may even return to the old letter grades for the fifth and sixth grades.

Sharon Collopy, a school board member, has been a Central Bucks parent for 21 years. Her youngest child got the new report card last year.

"When the administration introduced the changes, they told parents they hoped to avoid labeling children as A or B students," she said. Instead, "they labeled an awful lot of them M students."

610-313-8232@Kathy_Boccella