Hi C.:
Congratulations on schooling your children from home. That is a big committment and your child is quite lucky to have someone who can do that.
One of my jobs is actually as an on-line middle school teacher. I am located in CO, but there are other schools just like mine all over the country. We use a non-religous, core-knowledge based curriculum created by a company called K12. You can learn more about K12 at www.k12.com. There may be a school set up by K12 in your state, and if so, starting at kindergarten level, the curriculum is free. We are a public charter school where our students school from home with a parent and receive support from certified teachers online.
If you want more information about this, feel free to email me.
Good Luck!
J.