For those of you homeschooling your children with full-immersion Spanish, this is a gold mine of Spanish resources. The Mexcian department of education has an amazing online account with Issuu and they've uploaded 641 publications, all of them Spanish texts as far as I can tell (I haven't gone through all of them). They appear to all be centered around 1st through 6th. Lots and lots of great information here. Obviously, the history is focused on Mexican history, but you should be able to use the math, science and other resources for homeschooling here in the U.S.
I haven't used any of these, so if you have, please share your thoughts. Of course, you should look through it first and see if it is of use to you. Just for fun, I'm sharing one book below and will try to remember to do so every now and then as a reminder.
**For those of you looking for a comprehensive list of Spanish learning programs, click here to see my post dedicated to them.
Enjoy!