I learned about this site from an amazing educator, Kristin Thomsen (@iEngagedTeacher). Readlist allows you to "bundle" webpages and compile them into an eBook. Once you have the eBook, you open it into Subtext and all of your articles are within its pages.
Here's how you do it:
1) From the Readlist site click, "Make a Readlist" in the upper right corner. With an account, you can save your sites, but I don't use that feature.