In this chapter, Julian Betts and Y. Emily Tang show us that there is strong evidence that charter schools are outperforming other public schools in many ways. But their analysis of existing charter school outcome studies also indicates that:
- Charter school studies are highly varied in quality: only about a third of all charter studies can be trusted to give a fair picture of whether students are better off in a charter school or not.
- High-quality studies are more likely than weaker studies to find positive charter school results on student learning, in both reading and math.
- Even high-quality studies show tremendous variability in results. Charter schools perform much better in some localities than in others. Elementary charter schools, in general, appear to outperform charter middle and high schools.
Variation in charter school results has been a source of criticism in the past, with some observers lamenting mixed results. Betts and Tang argue, however, that a high degree of variation in achievement outcomes is an entirely predictable and possibly even a desirable short-term product of charter schooling. Since innovation and experimentation rely on diverse strategies and some risk taking, both failures and successes are to be expected. Local variation, again with different results, is also a factor that needs to be taken into account. Some localities and local charter schools have a very good grip on what they are trying to accomplish; others are hoping for the best.
In the long run, the success of the charter movement will depend on whether it is able to build on successes and abandon failures. To reinforce success and eliminate failure, we need to understand what explains these variations. A second generation of achievement research in these areas is urgently needed.