One of the free resources that I came across and used with my oldest daughter (for a bit) was the Student's Friend World History Textbook. It is an online textbook but also available in PDF form. It's really a bare bones textbook, not loaded down with a lot of extra facts; it is as it is described, a concise world history.
Now, when I used it, I did do a lot of supplementing to make it come "alive" (I made some materials or found videos and PowerPoints) but it worked great as a spine. In addition, there is a page of support materials where you will find links to maps and project/assignment ideas.