California's Charter Schools: 2008 Performance Update
June 2008
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California's Charter Schools: 2008 Performance
Update, EdSource's fourth annual analysis of the state's charter schools, yields findings that are similar to last year’s report. Both years' studies control for
the size of schools and the backgrounds of
the students they serve in order to estimate
the effect of their status as charter or noncharter
schools on student achievement.
Key Findings:
Performance of Charters vs. Noncharters
Charter elementary schools have lower average API scores
The 196 charter elementary schools in this
analysis are, on average, about 70% of the size
of the noncharter elementary schools, and they
serve somewhat more advantaged students.
After adjusting for differences in school
size and School Characteristics Index (SCI)
values, charter elementary schools score 9 points
lower on the API, due mainly to charter
students' scores on the California Standards
Test in mathematics, which are lower by
statistically significant margins. But when the
25 nonclassroom-based charters are excluded
from the analysis, charters' deficit on the API
disappears, the difference in math shrinks, and
their advantage in English grows slightly.
Charter middle schools outperform noncharters
The 57 charter middle schools are about one-third
the size of noncharters on average, and
they serve more disadvantaged students.
After adjusting for differences in school
size and SCI values, charter middle schools
score 45 points higher on the API. The findings
are consistent across other performance
measures and have also been stable over time.
Charter high schools have higher API scores
but lower math scores than noncharters
The 130 charter high schools are about one-fifth
the size of noncharters, on average, and
generally have lower SCI values.
After adjusting for differences between
charters and noncharters in school size and
SCI values, charter high schools score 14
points higher on the 2007 Growth API,
despite lower scores in mathematics. When
the 50 nonclassroom-based charters are
excluded, charter high schools score higher
than noncharters on all measures, including
mathematics.
Along with these findings, this analysis offers a wealth of other comparisons and insight on the state's charter schools including:
- Within Charter Comparisons—CMO Charters vs. Non-CMO Charters
A substantial portion of the growth in the
state's charter school segment in recent years has
come from the creation and expansion of charter
management organizations (CMOs). These
schools represent nearly one-fifth of the charters
in this study. CMO charters, on average,
outperform other charters; but not all CMO-run
charter schools are high achievers.
- District Profiles: Los Angeles, Oakland,
and San Diego Unified School Districts
In three of the state's largest districts, Los
Angeles, Oakland, and San Diego, charter
schools have become relatively common. This report
contains separate performance comparisons
of charters and noncharters in these districts.
This summary only skims the surface of the information available in this report. You will also find detailed "Vital Stats" on the state's charter schools as well a look at how closely districts are matching the state's new achievement benchmarks for charter school renewal. Purchase the full report now.
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