Without advance warning, the Florida Department of Education released 2018 school grades Wednesday in a midday email that caught school districts unaware.

The bottom line showed a continued increase in A-rated schools and decrease in F-rated schools. Nearly all schools that received an F in 2017 saw an improvement of at least one letter grade.

Gov. Rick Scott touted the results in a press release.

"Our years of historic investment in Florida's K-12 education system are paying off," Scott said. "The ability to get a great public education empowers our students to live their dreams in Florida. This is why since 2011 funding for Florida's K-12 public schools has increased by $4.5 billion."

Several analyses have shown that Florida's education funding, though up in total dollars, has not reached pre-recession levels when accounting for inflation. This year, school officials have noted that the amount of added discretionary money per student rose 47 cents, with the rest of the extra funding earmarked for specific purposes such as increased school security.

Cynics of the grading system were quick to point out their doubts about the system and the positive spin offered by state leaders.

"Shocked, shocked to see a fraudulent measure go up in an election year," Polk County School Board member Billy Townsend said on Twitter. "School grades are fraud, whether they go up or down. End them."

Still, many parents have come to rely on the marks as a way to gauge whether their children's schools are performing well on key state tests. Real estate agents often use the grades to help sell homes.

The grades take on even greater significance this year for another reason: Schools with continued poor results of D or lower face takeover by outside entities, with the possibility of a district-managed turnaround abolished by the state Legislature.

For Foster, Sheehy and Oak Park elementary schools in Tampa, that's bad news. Oak Park got an F, and Sheehy and Foster received D's, meaning the Indiana-based consulting group Phalen Leadership Academy is in charge, effective Monday.

Hillsborough's Potter, Booker T. Washington and Mort Elementary, and Memorial Middle School, by contrast, saw enough improvement to remain under district control. Potter earned a C after five consecutive F grades. Washington also made a C after three straight F's.

"This is a direct result of our priority in closing the achievement gap and ensuring that all students succeed," said School Board member Tamara Shamburger, who represents the area. "We still have a lot of work to do to ensure those results are sustained at a minimum, but hopefully improve."

Other area schools that have struggled saw mixed results.

Campbell Park and Lakewood elementary schools in St. Petersburg saw their grades drop back to F, putting Lakewood under the control of a private organization. Fairmount Park Elementary, another school featured in the Tampa Bay Times 'Failure Factories' series, improved from F to D, and Azalea Middle rose from F to C.

Both avoided following Lakewood into Learning Science International management.

Moton Elementary in Brooksville, which fired its teaching staff in anticipation of a needed turnaround, improved from D to C, removing itself from the state accountability list.

Related: School grades: Hernando County schools steady at a B, but troubled Moton Elementary moves up

Pasco County saw five of its west-side low income schools — Chasco, Richey, Hudson, Anclote and Calusa — all decline from C to D. West Zephyrhills Elementary, the campus most at risk of a takeover plan, improved to C, to get off the list.

Overall, Pinellas County had 36 A's, 24 B's, 61 C's, 9 D's and 5 F's. Notable developments included C grades for Curlew Creek, Lakeview Fundamental and Leila Davis elementary schools, all of which are perennial A or B schools. Meanwhile, Southern Oak Elementary went the other way, upping its grade from a C to an A.

In Hillsborough County, the number of traditional schools with F grades rose from two to five with Kimbell, Shaw and James Elementary, and Sulphur Springs K-8 dropping to F's as well.

Sixty-five charter and district schools earned A grades, up one from 64 in 2017. Woodmont K-8, a Charter Schools USA-run school that the district was watching closely after three consecutive D's, improved to a B.

"Everyone is looking at the data to see what supports their schools are going to need," said district spokeswoman Tanya Arja, noting that all of the district-run high schools earned a C or better.

Pasco County had 24 A's, 19 B's, 36 C's, 5 D's and no F's. Among the movers were Denham Oaks and Trinity Oaks elementary schools; Weightman Middle School; and Sunlake, Wiregrass Ranch and Mitchell high schools, which all rose to A from B. On the other end, Pine View Elementary fell to C from A.

Hernando County overall was rated a B. Of the district's 25 schools, there were six A's, five B's, 13 C's and one D. Four schools improved their grade from last year, six dropped a letter grade, and the rest earned the same grade as in 2017.

Other districts' officials, caught offguard by the unanticipated release, said they had not reviewed the results and had no immediate comment.

– Staff writers Marlene Sokol and Megan Reeves contributed.