Nobody has yet studied the phenomenon, but there are some illustrative examples:
• Student ministries that started before the school prayer ban, or just after, have expanded to reach tens of thousands of public school students. Since the mid-1960s, the Fellowship of Christian Athletes has established itself on more than 8,000 junior and high school campuses, many of them public. And Campus Crusade for Christ, founded in 1951 as a Christian ministry to college students in California and now known as Cru, has helped high school students start some 200 Christian clubs, almost all of them in public schools. Youth for Christ, an evangelical missionary organization in which broadcast-evangelist Billy Graham worked in the 1940s, began reaching out to high school and middle school students in the 1960s and '70s. It now has on- and off-campus clubs at 1,200 schools, most of them public.
• At the elementary school level, religious instruction sometimes takes place right on campus in after-school programs. By far the most widespread and controversial, Good News Clubs hold Sunday school-like classes in some 3,200 public elementary schools. After-school Good News Clubs have grown from fewer than 17,000 participants in 2001 to more than 156,000 enrolled in 2012.
• "See You at the Pole" began in Texas with 10 Christian students praying around their school flagpole in 1990. It has blossomed into a yearly ritual involving 1 million to 2 million public school students nationwide meeting on a designated September morning before class.