I created a simple child theme for twenty eleven.
I put the @import line in the style.css file inside the twentyeleven-child folder.
So far, so good.
I then modified a copy of footer.php, and put that in the same twentyeleven-child folder.
I activated the Twenty Eleven Child theme.
Chaos is the result: the site appears broken, and has some miscellaneous text displaying here and there. All I did in the footer.php file is to change some text in the div#site-generator.
If I make the same changes in footer.php, and load the new file into the twentyeleven folder (NOT the child folder) it works normally, and shows my changes.
I suspect I am missing something here.
TIA for your suggestions!