Abstract
The third National Charter School Study aimed to test whether charter school
were effective and to highlight outcomes on academic progress. The results
showed that typical charter school students outperformed similar students in
noncharter public schools by 6 days in mathematics and 16 days in reading. The
key metric used to claim better performance in charter schools is "days of
learning." In this report, the origin of the days-of-learning metric is
explored with NAEP data, and the interpretation of days of learning as
within-year growth is considered.