The schools specialize in math, science or the arts. Some are Afro-centric, others are religious. They are publicly funded but operate independently of local schools boards and, often, teacher unions.
They all make up the growing charter school movement that the Obama administration would like to see flourish.
"The charter movement is absolutely one of the most profound changes in American education, bringing new options to underserved communities and introducing competition and innovation into the education system," Education Secretary Arne Duncan told attendees at the National Alliance for Public Charter Schools' annual conference last week.
But not everyone agrees that charter schools should play an integral role in education reform.
"You should have a reason for increasing charter schools, and I haven't seen any rationale for doing that except for, 'Let's do it,'" said Gerald Bracey, an associate at the High/Scope Educational Research Foundation.
With $100 billion in stimulus funding for education, including $4.35 billion in the competitive Race to the Top fund to improve education quality, Duncan has offered a stern warning to states: Embrace charters or risk losing stimulus dollars.
"States that don't have charter laws or put artificial caps on the growth of charter schools will jeopardize their applications under the Race to the Top fund," Duncan told reporters last month. "Simply put, they put themselves at a competitive disadvantage for the largest pool of discretionary dollars states have ever had access to."
Governors are heeding Duncan's warning. On Monday, Tennessee Gov. Phil Bredesen signed a measure that expands the eligibility requirements to attend charter schools. On Tuesday, Indiana Gov. Mitch Daniels signed into law a budget that does not limit the establishment of new charter schools.
"He's blackmailing states, saying you either have to have charters ... or lift the caps, or your stimulus money will be at risk. There's no evidence out there to justify it," Bracey said.
A recent report by Stanford University Center for Research on Education Outcomes found a wide variance in quality among charter schools and reported that many students in charter schools are not performing as well as students in traditional public schools.
Last week, Duncan called the report "a wake-up call, even if you dispute some of its conclusions." But Duncan's reaction shocked Bracey.
"There are numerous studies out there showing that charters, compared to public schools, don't do as well," Bracey said.
Citing the Stanford report, Duncan warned charter school management that low-performing charter schools are endangering the success of their own movement and must be turned around.
"The charter movement is putting itself at risk by allowing too many second-rate and even third-rate schools to continue to exist. Your goal should always be quality, not quantity," Duncan said.
When he was head of the Chicago public school system, Duncan helped open 70 charter schools, but he also closed down three for academic failure and mismanagement.
Duncan went on to challenge charter operators to improve accountability.