Umbrella school-"is an alternative education school which serves to oversee the homeschooling of children to fulfill government educational requirements."
http://en.m.wikipedia.org/wiki/Umbrella_school
Basically, they set the requirements you have to meet and keep records for you of grades and attendance. They provide transcripts and things if you need them for transfer back into school, public or private, if you ever decide to go back. They are also your legal proof that you are actually homeschooling your child.
In general, you have to go through the public school system and declare your intent to homeschool following all state regulations or have an umbrella school. An umbrella school is a way around having to follow the state regulations. In general, where we live it is a given that you stay away from anything that puts you in the state's sight. The public schools and truancy offices give a lot of people a hard time, and most people here feel any public involvement should be avoided at all costs to prevent future problems, so everyone here uses an umbrella school.
Gateway is a common popular umbrella school where we live. Faith Christian Academy is the private umbrella school I was talking about earlier. It is out of Pigeon Forge.
There are different levels of umbrella schools that offer varying levels of support and guidelines. For instance Gateway only requires 4 hrs of school a day, and the minimum basic classes English, math, etc. Its very lax. You can pretty much do whatever you want as long as you turn in an overall grade for each subject they require and meet your hours. You can use any curriculum you want or even unschool.
Other schools, like the private one I mentioned, have much stricter requirements. It depends on what you are looking for. We were looking for a strenuous private university prep type school, just without the tuition costs. As a high school student, I was required to take 4 credits of all the basics - math, history, science, grammar, reading, as well as 4 credits of a foreign language, plus classes in logic and Latin, and complete a minimum 6 hrs a day. It was the best college prep I could have asked for. Most people, however, aren't looking for that level of control from their umbrella school. We had to use the curriculum recommended to us or an alternative they approved. We had to turn in multiple grades throughout the year, not just an overall grade. They required all this because they issue a private school diploma that is equal to the diploma you would receive if you attended their actual physical private school, so they have to make sure you are meeting all the same criteria and are at the same level as all the kids who attend the actual private school. It worked out really great for us having such detailed high school records and a real degree.
However, while this level of oversight can be good for a very academic college bound high school student, I wouldn't recommend it for the lower levels. That's why most of the people who homeschool around here use the private school for the testing and evaluating services, but then use Gateway as their umbrella school. This way they can get an idea of where their child is, what he/she needs to work on, maybe even some ideas for curriculum, but can still pick and choose what they want to do or not do themselves. This is how we did it for my younger sister when she was elementary school.
