The Center for Education Reform has produced a handy 4 page flyer, Charter Schools: Quality Educational Options that Improve All Schools, to explain charter schools in brief, straight forward language. It describes the role of authorizers, the difference between strong and weak charter statutes, the constitutionality of charter school laws, the rationale and accountability of charter schools and more.
Their website contains a host of other information including state by state ranking of charter school laws and other general education reform news and policy information.