Very doable with the library and the internet. Actually, it might be a better education. Textbooks can be very limiting and boring. Less learning takes place. Remember that no kid is going to cover every subject. Find out what your kids want to learn.
math: I'd use Abeka--it's pretty cheap and very easy to implement. abeka.com/
history: read your way through history as a guide and fill in with library books and videos
fisheaters.com/lists.html memorize and be able to explain
the Baltimore catechism is online, too.
handwriting: buy a notebook and write a Bible verse every day. Have them copy it underneath
spelling: spellingcity.com/ Or, just choose words that they miss often
science: I tend to go with real books and videos. In addition to library videos, check netflix and online videos. I like mythbusters and nova. Have them pick a topic they are really interested in and just dive in. You can keep a journal or a notebook to keep track. You can also go the Nature study route. Just look up a few websites on this.
English: For grammar, I'd just incorporate it into their writing projects. I've found that my kids tend not to remember grammar when I teach it separately anyway.
Composition. I like EIW--excellence in writing. The neat part about it is that you, the teacher, learn how to teach it and then you implement it. The best thing is to buy the binder and borrow the videos.
Geography: sheppardsoftware.com/web_games.htm click and drag maps. my kids love these
art nga.gov/kids/ there's other fun ones, too.
music history and appreciation classicsforkids.com/
There's so much you can do with museums and fieldtrips, too.
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