I got started with WordPress a few months ago (June/July) and am pretty sure, say 95% sure, that I learned very quickly to use child themes and didn't touch the original.
I am not 100% sure though, and see that the theme I use, twenty-eleven, has an update.
How can I verify that I did use a child theme for all of my changes? Any files I can look at and compare to the original twenty-eleven theme (the one that was current before the update this week) to be sure? I'd like to find any such changes and move them to the child theme before updating.