Pages doesn't back up to iCloud

What am I not understanding?

I'm using Pages 5.6.1 on a Mac Mini, mid-2011, running El Capitan 10.11.2.

I am logged in to iCloud and Pages is set up in the iCloud Preferences settings.

When I create a document on my Mac, I expect it to be backed up to the Pages section (folder) of iCloud Drive. It doesn't. The only way to get a document into iCloud is to expressly Save it there.

I thought that as I modify and save Pages documents on the Mac, they are updated and backed up to my iCloud Drive. But the only way I can get them in there and have them available to my other devices is to work completely in iCloud. Then I have to expressly save them to my Mac if I want them phusically on my hard drive.

What am I doing wrong?

Rich

Mac mini, OS X El Capitan (10.11.2)