Seventy percent of Louisiana’s public high schools showed double-digit growth in their school performance scores this year compared with just 2 percent of elementary and middle schools.

Similarly, 40 percent of “combination schools” — usually high schools that feature middle or elementary grades — saw their school performance scores grow by 10 points or more.

It’s the reverse of the past decade when the lower grades, particularly elementary schools, were typically the engines of Louisiana’s academic growth.

The state as a whole increased its performance score 5.7 points, from 94.8 to 100.5, which is the second-highest improvement rate in the 13 years Louisiana has rated its public schools.

The vast majority of high schools, 86 percent of them, outdid the state’s growth rate. Many of these schools jumped up one or two letter grades, earning financial rewards in the process.

These strong results were released Oct. 22.

In an interview earlier this month, state Superintendent of Education John White attributed the striking high school numbers to across the board increases in both graduation rates and improved results from four separate end-of-course exams that high school students take.

He described these as new challenges implemented in high schools in the past few years.

For instance, graduation rates improved from 67.2 to 70.9 percent overall — a handful of schools increased their graduation rates by 20 percent or more. White said while more students are staying in school, schools also are getting better at data keeping.

Meanwhile, passage rates for end-of-course tests in algebra, English, geometry and biology all showed at least a little growth. Biology showed the most gains, with student passage rates improving by 9 percentage points.

“The schools met two different challenges at the same time,” White said.

The challenges are growing more challenging. Consequently, it’s possible that schools that improved a letter grade this year may drop back to where they were, or even decline.

Falling behind has financial consequences for public schools. F-graded schools are in danger of state takeover, and students at C-, D- and F-graded schools qualify for vouchers to attend private schools, taking with them money that would have otherwise gone to their public schools.

High schools, in particular, are being measured differently.

A quarter of a high school’s grade will, from now on, come from how students do on the ACT college placement exam.

Points that schools received for high school students who score “fair” on end-of-course exams, which equates to a little below grade level, are being discontinued. Also points that schools collected if students achieved special “diploma endorsements” are going away.

And all schools are in the process of shifting to the Common Core standards, adopted by 45 states so far, including Louisiana, as well as new standardized tests that rely on those new standards.

The highest possible school performance score will change as well. In the 2012-13 school year, it will change from 200 to 150.

The revised accountability system is being set up with the assumption that schools will do as well on the new measures as they did on the old. White acknowledged, however, that some schools may show declines as they adjust to new tests and new ways of measuring how they are doing. He said that’s a consequence of raising the bar.

“When you reach a point where you are good at what you were doing before, it’s a very natural thing to say, ‘Now let’s increase the challenge,’” White said.

White pointed out that growth in performance scores was not confined to high schools. Indeed, 76 percent of the almost 1,300 schools that earned scores in 2011-12 improved compared with the year before.

High schools’ performance score growth, however, far outpaced the growth in elementary and middle schools.

For instance, while 74 percent of elementary and middle schools improved at least some compared with 2010-11, more than 97 percent of high schools improved their scores during that same time period.

Indeed, only four out of 130 high schools declined, while 252 out of 956 elementary and middle schools declined.

Among high schools, Homer High School declined the most, 5.7 points. By contrast, North Webster Junior High School declined by 18.7 points. Both schools are in Webster Parish, northeast of Shreveport.

The disparity is clear at the top of the scale as well.

Walker Freshman High School in Walker grew 40 points, the most in the state. The fastest-growing performance score in elementary or middle school, John L. Johns Elementary School in Minden, grew half that much, by 20.8 points.

High schools used to be measured similarly to elementary and middle schools, but not so much anymore.

For years, 90 percent of a school’s score was based on standardized tests, the rest based on factors such as attendance and dropout rates.

In 2007, the formula for measuring high schools changed, but elementary and middle schools stuck with the old formula.

With the change, standardized tests accounted for just 70 percent of a high school’s performance score. The remaining 30 percent came from a new “graduation index.”

The index gives a growing number of points to students who stay in school, graduate and take extra courses connected with college or career preparation that earn them “diploma endorsements.”

The standardized tests also changed beginning in 2009. Graduate exit exams, which Louisiana students had been taking since the 1980s, were replaced by tests given at the end of individual courses.

Louisiana students have steadily improved on these end-of-course exams since then, and the year ending in 2012 was particularly strong.

Donaldsonville High School benefited from all of these circumstances.

This high school, which has languished in the academic cellar for years, jumped from 76.4 to 108.8 on its latest school performance score, an increase of 32.4 points. That was enough to allow the school to jump from a D to a B. The school’s score is now 8.3 points above the state average.

Donaldsonville High’s graduation rate helped, improving by 14 percent. And its end-of-course test results improved in three of four subjects, growing by double digits in geometry and English.

The school’s numbers were also helped when its seventh- and eighth-graders were moved to Lowery Middle School in fall 2011.

The school, however, still has a long way to go. While 60 percent of its students are at grade level or above in algebra, slightly better than the state, only 28 percent were doing as well in biology, a rate barely half the state rate of 52 percent.

The greater prominence of the ACT also may hurt the high school. In 2011, it had just a 16.3 composite ACT score. That’s 0.2 point below last year’s score. It’s a score well below the state average of 20.3 and the national average of 21.1.

The three schools that feed into Donaldsonville High also remain D and F schools.