A Beka scope and sequence nursery through grade 12
Time 4 Learning scope and sequence preschool through grade 8
BJU Press scope and sequence preschool through grade 12
I found a couple of textbooks at Goodwill and the Women's Shelter Resale Shop. A friend of mine who is no longer homeschooling gave me some books. Most of our "textbooks" will come from our public library and university library. I picked up a math workbook at the Women's Shelter for $0.59! And it just happens to be the level we need! If I hadn't found that, I was planning to buy the workbooks from Horizons. My cousin uses their math curriculum so I got to look over hers and I really liked it. I may use it next year.
The following sites have a variety of worksheets, activities, and crafts. Some of the activities would be fun for kids to do on the weekends or during summer, not just for homeschooling. Some of the sites are geared toward younger kids.
A to Z Teacher Stuff
Easy Fun School
The Home School Mom
Super Teacher Worksheets
If you've been homeschooling for a while, you probably have a list of favorite sites. If you're just getting started, I hope these will help you. I think I've got a science activity/experiment for every week! I'll probably be posting some sites by topic later. Having them categorized is helping me find what I want more easily.