A good paper to read about charter schools is “Getting Beneath the Veil of Effective Schools: Evidence from New York City” by Will Dobbie and Roland Fryer (shown above). They use this key fact: “New York law dictates that over-subscribed charter schools allocate enrollment offers via a random lottery.”

Here is Will Dobbie and Roland Fryer’s summary of some of the previous evidence about charter schools:

The results reported in this paper contribute to a growing body of evidence using admissions lottery records to document the effectiveness of certain charter schools. Students attending an over- subscribed Boston-area charter school score approximately 0.4σ higher per year in math and 0.2σ higher per year in reading (Abdulkadiroglu et al. 2011), with similar gains reported for students attending the Promise Academy charter school in the Harlem Children’s Zone (Dobbie and Fryer 2011), the Knowledge is Power Program (KIPP) schools (Angrist et al. 2010, Tuttle et al. 2010), and the SEED urban boarding school in Washington D.C. (Curto and Fryer forthcoming). Dobbie and Fryer (2012) find that students attending the Promise Academy charter school also do better on a variety of medium-term outcomes such as college enrollment and risky behaviors.

They focus on which among the charter schools are most effective. Their list of factors that seem to add to effectiveness is:

• frequent teacher feedback

• data driven instruction

• tutoring (a lot of it)

• a longer school day and longer school year

• a relentless focus on academic achievement

(In “Magic Ingredient 1: More K-12 School” I focused especially on the benefits of a longer school day and a longer school year.)

Here is Will Dobbie and Roland Fryer’s description of these factors and how they matter:

… an index of five policies suggested by forty years of qualitative case-studies – frequent teacher feedback, data driven instruction, high-dosage tutoring, increased instructional time, and a relentless focus on academic achievement – explains roughly half of the variation in school effectiveness. Using observational estimates of school effectiveness, we find that a one standard deviation (σ) increase in the index is associated with a 0.053σ (0.010) increase in annual math gains and a 0.039σ (0.008) increase in annual ELA gains. Moreover, four out of the five school policies in our index make a statistically significant contribution controlling for an index of the other four, suggesting that each policy conveys some relevant information. Controlling for the other four inputs, schools that give formal or informal feedback ten or more times per semester have annual math gains that are 0.048σ (0.023) higher and annual ELA gains that are 0.044σ (0.014) higher than other schools. Schools that tutor students at least four days a week in groups of six or less have annual ELA gains that are 0.040σ (0.020) higher. Schools that add 25 percent or more instructional time have annual gains that are 0.050σ (0.013) higher in math. Schools that have high academic and behavioral expectations have annual math gains that are 0.044σ (0.023) higher and ELA gains that are 0.030σ (0.015) higher.

They caution that there may be some factors all or almost all of the charter schools in their sample share that contribute to their effectiveness. This list of factors is about differences between charter schools.

In “Injecting Charter School Best Practices into Traditional Public Schools: Evidence from Field Experiments” (shown below) Roland Fryer argues that these practices also help non-charter schools do better. Notice how helpful charter schools have been in providing evidence about what works. And charter schools have shown a lot of success in implementing good practices.