Curricula in the United States vary widely from district to district. Not only do schools offer a range of topics and quality, but private schools may include religious classes as mandatory for attendance. This raises the question of government funding vouchers in states with anti-Catholic Blaine Amendments in their constitution. This has produced camps of argument over the standardization of curricula and to what degree. These same groups often are advocates of standardized testing, which is mandated by the No Child Left Behind Act.