Parental choice is so deeply engrained in American schooling that it is difficult to imagine an education system without it. Perhaps if the federal government determined where each family lives and offered no alternative to the local public school then we might approximate a choice-free system, but this type of thought experiment is absurdly detached from reality. The relevant question is not whether school choice is present in an area but which types of choice are available and their prevalence.
The most widely available types of school choice relate to residential school choice and the availability of private schools. In terms of the former, families can sort them- selves into the communities that best satisfy their preferences (Tiebout, 1956). This sorting happens not only across cities and towns but also within them, as families choose to live within school zones linked to desirable neighborhood public schools. Private school choice is similar in some ways to residential school choice. For example, this type of choice typically requires some degree of expendable resources. For families to choose where to live, they must not be constrained by prohibitively high property values, rental prices, taxes, moving costs, or other costs associated with selecting an alternative location. For families to choose private schooling for their children, they typically must cover the tuition costs. The prevalence of residential school choice is difficult to quantify, though it is clear that finding suitable public schools is a common consideration in relocation. The U.S. Department of Education estimated that approxi- mately 10.5 percent of American students in grades PK–12 in the fall of 2010 attended a private school (National Center for Education Statistics, 2010).
In addition to residential and private school choice, families in some parts of the country can choose schools through formal local, state, or federal policies. Charter school laws, which vary widely by state, allow for publicly funded, privately operated schools that families can select outside of their zoned schools. They promise greater school-level autonomy in exchange for greater accountability. Charter school enroll- ment has grown steadily over the past 20 years, with roughly 1.4 million students (approximately 3 percent of all students) now enrolled in one of the country’s nearly 5,000 charter schools (Christensen, Meijer-Irons, and Lake, 2010).
Private school vouchers that enable families to cover some or all of private school tuition costs entail another policy strategy for increasing school choice; this approach is closer to Friedman’s initial vision. The Alliance for School Choice (2010) reported that there were nine active voucher programs during the 2009–10 school year. There were nine other scholarship tax credit programs that offered tax credits to individuals and corporations who donated to nonprofit organizations providing scholarships to tuition-paying private school families (Alliance for School Choice, 2010).
Although charter schools and private school voucher programs receive the most public attention, a vast assortment of other policies increase parental discretion over how their children are educated. Home-schooling is an often-overlooked example.

source: http://scholar.lib.vt.edu/theses/available/etd-32498-155442/unrestricted/Chapter2.pdf