Curto and Fryer (2011) examine the effect of the DC and Baltimore, Maryland SEED urban public boarding schools modeled after the "No Excuses" charter schools. Students spend 5 days a week at the boarding school for student in grades 6-12. According to Curto and Fryer (2011):

"SEED schools have an extended school day, extensive after-school tutoring for students who need support, rely heavily on data to drive instruction, and have a paternalistic culture with high expectations. The middle school curriculum focuses on developing basic skills in reading and math, and the high school uses an intensive college preparatory curriculum that requires all students to take the SAT or ACT college admissions test and apply to at least five colleges or universities in order to graduate."

1. Explain why Curto and Fryer (2011) can't compare those enrolled at SEED to those enrolled in public schools to find causal estimates.

2. Curto and Fryer (2011) note that SEED selects students by random lottery when demand for the school exceed available admission slots. Explain how they will exploit this fact to find causal estimates of the effect of attending SEED schools.