Are virtual schools effective?

When people think about virtual schools, they think that it is all about technology but it's not. Virtual schools are about curriculum and instructions. In virtual schools you can join virtual classrooms whenever there is internet access. 

Virtual schools also have teachers. A computer is not just teaching them. The student is teached by a cerified teacher. In the best virtual schools, the teacher works directly with both the student and the learning coach. 

During my research I have a lot of things about virtual schools, but I can not decide whether virtual schools are effective. With more of my research I shall find out.