Most public school districts in the New Orleans metropolitan area saw declines this year in their school performance scores, with those in Orleans Parish taking a particularly bad dive.

Meanwhile, scores for publicly funded preschools, released for the first time this year, indicated that the institutions educating the metro area’s youngest learners are mostly capable.

Results from the combined scoring systems, released Tuesday, offer a complete picture of the performance by area institutions educating students from birth through high school.

[Click here to see full list of scores by school and district.]

Performance scores for K-12 schools, which have long been used to determine which schools are on track and which need state intervention, are awarded on a 0-150 point scale and are accompanied by letter grades of A through F.

They are based on things like exam scores, graduation rates, diploma quality, the course credits students earn and special points schools get when struggling students excel, dubbed “progress points.”

Preschools' scores, on the other hand, are awarded on a 1-7 point scale and are accompanied by ratings of “unsatisfactory,” “approaching proficient,” “proficient” or “excellent.”

Scores for younger students are based in part upon teacher-child interactions and instruction, and in part on things like a preschool’s number of credentialed teachers or its curriculum quality. Each school that receives public money is ranked.

For K-12 schools, the bleak news of declining scores comes on the heels of falling scores on state tests such as the Louisiana Educational Assessment Program.

The city's overall school performance score fell by a startling 14 points from last year, mostly because schools struggled to hit performance targets for their neediest students and did not receive the “progress points” they were awarded last year. The city’s overall letter grade dropped from a B to a C.

New Orleans schools also saw dips in their performance on LEAP and end-of-course tests, among other indicators, data show. Earlier this year, officials said the test score declines were a sign that progress achieved after the city’s post-Hurricane Katrina education reforms has started to slow.

A breakout of scores for schools governed under the locally controlled Orleans Parish School Board and the state-run Recovery School District was not provided. All the schools are due to return under the School Board’s umbrella within the next two years.

St. Charles Parish saw the second biggest drop, of about 9 points, also largely because of a failure to obtain "progress points." That district, did, however, hang on to its A letter grade.

St. John, St. Tammany and Jefferson parishes saw more modest declines. St. John, which last year hovered precariously close to the C range, went from a B to a C as a result of its decline. St. Tammany and Jefferson retained their respective A and C letter grades.

“Having a high district performance score affirms the work our educators are doing in the classrooms across our 55 schools to maintain achievement,” St. Tammany schools Superintendent Trey Folse said in a statement.

Plaquemines and St. Bernard parishes were the only metro area districts to see gains, of roughly 2 and 4 points, respectively.

The New Orleans area's lower scores were in contrast with the state’s overall performance, which increased by nearly 4 points.

Follow Jessica Williams on Twitter, @jwilliamsNOLA​.