Columbia County schools overall scored above the national average on the most recent Iowa Tests of Basic Skills.
As a whole, the school system jumped one to two percentile points at the three grade levels tested, with the biggest gain of four points in fifth-grade language arts.
But individual schools varied in certain areas with some making gains of more than six to 10 percentile points and others dropping.
For example, Evans and Columbia middle schools both had a six-percentile-point increase in eighth-grade language arts.
Columbia Middle also had a seven-point increase in social studies and an eight-point increase in math.
"The one- to two-point differences that go up or down -- that will happen any given year," Evans Middle Principal Jeff Carney said. "But when you have a six-point increase in one area in one year, that's significant."
The ITBS are norm-referenced tests comparing schools or school systems to a national average of 50. Tests are given to pupils in the third, fifth and eighth grades with percentile ranks indicating how many test scores in the national norm group were lower than a particular school or system.
Sub-tests are given in areas such as reading, mathematics, language arts, social studies and science.
Elementary schools had a variety of gains and drops in the test areas.
Martinez Elementary had a 10-point drop in language arts and a six-point drop in science at the third-grade level.
Euchee Creek Elementary had seven-point increases in third-grade language arts and math and a five-point increase in fifth-grade language arts, but a nine-point decrease in fifth-grade science.
Euchee Creek Principal Wanda Golosky said the school did not have the dramatic increases it had last year, but maintained its scores in some areas and continued to increase in others.
The school, she said, has concentrated on small-group instruction and reading skills to help maintain scores.
"We're pleased with what we're doing, " Ms. Golosky said. "Maintaining was our big test."
While principals said they look closely for dramatic shifts in percentile scores from year to year, they usually prefer to look at trends instead of comparing two different groups of pupils.
Riverside Middle School Principal Charles Nagle said while the school dropped points this year in every test area, last year the school had scores higher than normal.
This year the school still surpassed the national average by more than 20 percentile points.
"These scores this year are good," Mr. Nagle said. "They're above national average."
Mr. Nagle said his school will be looking at the eighth-graders past test performances to give the recent ITBS scores more meaning.
"I can't compare these students to last year's students because that's comparing apples to oranges," he said.