That's how they like to pitch in sales, anyway. There are two problems which it hopes you won't know to ask about:
1. Most of the big claims about charter school performance is due to small sample size or short measurement time. There's a notorious cycle in the field where someone announces that they have a brilliant way to make kids succeed and publishes results which get a lot of attention, but regression to the mean sets in once they try to scale it up or have more than a few years worth of data. Once you get enough data they perform very similarly to the public schools serving the same community — worse as often as better.
2. Schools which show consistently better performance are the ones who can select students who were higher performing when they enrolled. If you can consistently attract richer, educated parents to your school — say with a pitch telling everyone how it's the best possible education for their children — you will post great numbers but those kids would have done well almost anywhere. This can be overt in the states which allow test-in or in the structure of the school (i.e. hit students with enough outside homework and you're going to lose a lot of kids who don't have family resources to support that extra time) or hidden in other areas: for example, a school in a state which doesn't require schools to offer free/reduced lunch will exclude poor kids without explicitly doing so, as will not offering bus service in a suburban area, having limited support for anyone with special needs, etc.
When evaluating schools, you have to do a value-added analysis comparing like cohorts of students. Public schools serve both a greater number of students and a much higher degree of diversity and very few are truly “bad” as — what you're usually seeing is that poor kids have more obstacles to success, and the United States runs a lot of special needs support through schools, and averages hide that information. I live in Washington DC which has tons of charters and there are a couple which have some great things for certain kids but not everyone (e.g. a language immersion) and a whole bunch which look pretty similar to the data from the local public schools when you match for equivalent parental SES.
1. Most of the big claims about charter school performance is due to small sample size or short measurement time. There's a notorious cycle in the field where someone announces that they have a brilliant way to make kids succeed and publishes results which get a lot of attention, but regression to the mean sets in once they try to scale it up or have more than a few years worth of data. Once you get enough data they perform very similarly to the public schools serving the same community — worse as often as better.
2. Schools which show consistently better performance are the ones who can select students who were higher performing when they enrolled. If you can consistently attract richer, educated parents to your school — say with a pitch telling everyone how it's the best possible education for their children — you will post great numbers but those kids would have done well almost anywhere. This can be overt in the states which allow test-in or in the structure of the school (i.e. hit students with enough outside homework and you're going to lose a lot of kids who don't have family resources to support that extra time) or hidden in other areas: for example, a school in a state which doesn't require schools to offer free/reduced lunch will exclude poor kids without explicitly doing so, as will not offering bus service in a suburban area, having limited support for anyone with special needs, etc.
When evaluating schools, you have to do a value-added analysis comparing like cohorts of students. Public schools serve both a greater number of students and a much higher degree of diversity and very few are truly “bad” as — what you're usually seeing is that poor kids have more obstacles to success, and the United States runs a lot of special needs support through schools, and averages hide that information. I live in Washington DC which has tons of charters and there are a couple which have some great things for certain kids but not everyone (e.g. a language immersion) and a whole bunch which look pretty similar to the data from the local public schools when you match for equivalent parental SES.