There is a growing body of literature comparing the effectiveness of charter schools and traditional public schools. No consensus has yet been reached, but there are persistent concerns that performance differences might be due to "better" students attending charter schools. Researchers must therefore first determine whether charter school students and traditional public school students are substantially different before they can attribute any achievement differences to the education provided by these schools.
This study examines nearly 158,000 test scores of more than 60,000 Arizona students attending 873 charter and traditional public schools statewide over a three-year period. Its purpose is to determine the net effect of attending either type of school on Stanford Achievement Test, V9, (SAT-9) reading achievement scores and total achievement growth over time.
Findings indicate that charter school students, on average, began with lower test scores than their traditional public school counterparts, and showed overall annual achievement growth roughly three points higher than their non-charter peers. Charter school students who completed the twelfth grade surpassed traditional public school students on SAT-9 reading tests.
However, achievement growth varies by grade level. In the elementary grades, charter school students exhibited faster achievement growth than traditional public school students. Achievement growth in the middle grades was similar for both kinds of students, while high school achievement growth was higher for traditional public school students. One reason for this is that elementary charters are more likely to focus on academics, while middle and high school charters generally serve students who want vocational training, have been out of school, have learning or behavioral problems, or those who have been in the juvenile justice system.
There is growing public concern over early education and dropout prevention. This study finds that charter schools are providing solid early education that propels students through the advanced grades, even though they had lower achievement test scores on average than their traditional public school peers. Charters also reach at-risk students in the middle and high school grades who might otherwise have slipped though the cracks.