I found an awesome website that is all inclusive with curriculum for grades K-12. It's called CK-12. Their Mission Statement is just the best :
We, at CK-12, believe every child on this planet should have equal access to great education
Don't you agree? Every child on this planet should have equal access to a great and quality education and I think that they have just about covered it with their wide range of subjects covered.
There's Astronomy, Physics, Biology, Math, Algebra, Trigonometry, Earth Science, Technology, Engineering, just to name a few.
My girls just started using CK-12 to supplement their Living books curriculum and so far, so good. I think that it gives them a chance to do something and learn under different terms via the computer.
CK-12 is free to join and offers a full year of curriculum. You (as a homeschooler and Parent) can sign up as a teacher, assign each individual child a membership and connect them to your teacher's account through a "classroom/group". Through the groups, you can set up assignments and tests and due dates per child and the child will receive a note in their inbox. It's so simple.
So go to CK-12 and check it out, again, it's free so you aren't losing anything by checking it out. You will only gain a new set of free online curriculum if you do. I like it, and so do my kids.