Two weeks ago, Mike Huckabee, a former governor of the southern state of Arkansas, won what many considered a surprise victory in Republican presidential caucuses in the nearby state of Iowa. Once considered a fringe candidate, Huckabee surged for a number of reasons. And one that's often cited is the impassioned support he received from thousands of Iowa home schoolers. These are parents who reject public schools and teach their children themselves in their homes. Many are evangelical Christians like Huckabee.

Nationwide, there are an estimated half-million American households in which parents do not send their children to school. Instead, one or both parents gather books, prepare lesson plans, and teach children everything from algebra to zoology. This can be costly, since one parent almost certainly must stay home rather than hold a job.

Home schooling is nothing new in America. But it took hold as an organized movement in the 1980s among religious conservatives. The home-schooling movement has since broadened to include parents of all faiths, or none at all.

In home-schooling households it's not unusual to find several children, ages 4 to 16, being taught together. Older kids help teach younger ones, as they once did in America's one-room schoolhouses.

Parents who prefer to educate their children themselves point out that in a schoolroom, where a teacher must instruct 25 or more students at a time, lessons roll along with little opportunity to stop and help those who are falling behind. Home-schooling parents say their kids have a better chance of being independent thinkers and hard workers.

One criticism of home schooling is that the parents who teach are often not trained or supervised. Another is that children are isolated and miss out on valuable school and social activities. Home-schooling parents reply that their kids go to scout or church meetings, play sports, and shop at malls with friends, just like schoolchildren. And because their study schedules are flexible, activities can be more easily arranged any time of day or night.

And one of those activities, for thousands of home-schooling families in Iowa recently, was getting involved in presidential politics.