Charter Benefits Are Proven by the Best Evidence According to
the Global Report Card, more than a third of the 30 school
districts with the highest math achievement in the United States
are actually charter schools. This is particularly impressive
considering that charters constitute about 5% of all schools and
about 3% of all public school students. And it is even more
amazing considering that some of the highest performing charter
schools, like Roxbury Prep in Boston or KIPP Infinity in New
York City, serve very disadvantaged students. As impressive and
amazing as these results by charter schools may be, it would be
wrong to conclude from this that charter schools improve student
achievement. The only way to know with confidence whether
charters cause better outcomes is to look at randomized control
trials (RCTs) in which students are assigned by lottery to
attending a charter school or a traditional public school. RCTs
are like medical experiments where some subjects by chance get
the treatment and others