An umbrella school, also called a cover school, "600" school, or a church school, is a term used to describe a private school for homeschoolers. A homeschooling family enrolls in an umbrella school as homeschoolers instead of establishing a home education program with their district school. In other words, the homeschooling family provides their children's educational information to the umbrella school (e.g., attendance records), not the public school (e.g., annual evaluations). When students are enrolled in an umbrella school, they are considered private schooled students, not homeschooled students, even though they are still being educated at home.
Many umbrella schools exist solely to help you comply with your state's compulsory school attendance laws. There is no actual school building and it is up to you to decide on the curriculum used and how and when your children are taught. All umbrella schools are required by law to maintain certain records, which will vary depending on your state, so be prepared that you will have to provide certain personal information.
Some umbrella schools offer more. You will find that different umbrella schools offer different features, such as field trips, scholarships, report cards, or diplomas. Some offer a full curriculum, and some have an actual school building. Different umbrella schools will also require different records and some will require you share the same faith. Before you register with an umbrella school, make sure you understand their requirements and that their school meets your family's needs.