Katoure Monette, a student in a K-1-2 multi-age class at the Harriet Tubman Charter School, shows Louisiana state superintendent of education John White an exercise of spelling words next to images in New Orleans, La. Monday, Nov. 6, 2017. According to the department of education, the school implemented a K-2 Montessori program in 2016 to provide students with greater focus, ownership of work, and accelerate student growth. Students have a two-hour work block in both the morning and afternoon to choose their own independent work 'on the shelf' while instruction in math and English Language Arts happens in small groups. White is taking part in a statewide tour of schools.

Louisiana's drive to meet higher standards for A-rated schools stalled during the past school year, according to state figures released Tuesday.

The percentage of students who earned the fourth highest of five achievement levels – mastery – or higher was unchanged for the 2016-17 school year compared to the previous year.

Just one in three students – 33 percent – scored mastery or better when English/language arts, math and science scores are combined. That is the same as the 2015-16 school year.

They are important because mastery represents the new standard for achieving top-school status, and Louisiana clearly has ways to go to meet the raised academic bar.

The results were part of the annual announcement on how public schools are faring, and what letter grades they earned.

The overall average for public schools is a B, up from a C last year.

The Zachary school system was ranked No. 1 for the 13th consecutive year.

While letter grades still spark arguments, they are used as a simple way for parents and other taxpayers to see how public schools are faring.

The exams, which are taken in the spring, are called the Louisiana Educational Assessment Program, or LEAP.

A total of 42 percent of students scored mastery in English/language arts, up from 41 percent last  year.

In math, 32 percent of students did so, a decline from 34 percent in the previous year.

Another 24 percent of students reached mastery in science, the same as the 2015-16 school year.

"We have raised academic expectations in Louisiana in order to prepare more students for success in college and the workplace, and it is encouraging to see our students and educators embracing these expectations and achieving at levels competitive with other states," state Superintendent of Education John White said in a statement.

"But there remains more work to be done," White said.

The results apply to students in grades three through eight.

Under the previous rules, schools could earn an A-rating if students averaged the third highest of five scoring levels – basic. That bar is gradually being raised, and students will have to average mastery, and meet other standards, for a school to earn an A-rating by 2025.

"No question that this system is getting more challenging in future years," White told reporters Tuesday. "If history stands as a precedent then schools will meet that challenge."

State officials often note that, in previous years, test scores have gradually rebounded, after an initial dive, when the academic bar is raised.

Changes in how students and districts are graded have sparked months of arguments in education circles, including Louisiana's top school board.

The percentage of students who scored mastery since 2015 has inched up in all three subjects.

That includes English, up 5 percentage points; math, 2 percentage points; and science, 2 percentage points.

Historic gaps between white students and black students, and different income levels, showed up too.

A total of 45 percent of white students earned mastery for the 2016-17 school year compared to  19 percent of black students.

Just 25 percent of students classified as economically disadvantaged scored mastery compared to 52 percent of those from families with higher incomes.

Students without disabilities earning mastery outpaced those with disabilities by 24 percentage points – 35 percent to 11 percent.

"The results provide further evidence that we must do more to close gaps that persist between historically disadvantaged students and their peers," White said.

The results mark the last time that the state will use a curve in allocating scores for schools and districts. The generous scoring, which lasted for four years, was started during the move to more rigor in English, math and other subjects.

Boosting the standard for A-rated schools is aimed at addressing the state's longtime gap in achievement requirements here and elsewhere.

"We can say an A-rated school in Louisiana would be an A-rated school in Massachusetts, California and anywhere in between," White told reporters.

School districts are assigned school performance scores based on test results, and those scores are linked to letter grades.

The Livingston Parish School District got a waiver because of the 2016 flood, and the East Baton Rouge Parish school system got something similar.

After Zachary the top-scoring school districts are the Plaquemines, Central, Ascension and Vermilion systems.

Much of Tuesday's announcement focused on an online reporting system that spells out how well child care centers, not just schools, are preparing children from birth through 12th grade.

The system, called Louisiana School Finder, is the first of its kind in the nation, state officials said.

Follow Will Sentell on Twitter, @WillSentell.