Hi, featheredfarmer! I homeschooled my daughters for a bit more than three years, and ebooks were a large part of how we managed.
Unfortunately, there are no ereader devices that are really good for academic use. The best are probably the tablets, like the android you're looking at. A laptop or netbook is probably better for notes/annotations/additional research, but might not be better enough when balanced against the larger size and being more bulky to use.
The best way to use ebooks for education is on a computer, whether that's desktop or laptop. That way you can have a word-processing program to write an essay while the book is open, or a note-taking program, or compare ranked lists of books, or whatever. (I'm not saying, "you should use a computer." I'm saying, "if you've looked at ereaders and can't find one that seems to fit what you need--it's not just you. They really aren't well designed for educational use.")
For "simple to operate," look to the Kindle. They're inexpensive, have basic web access, and are designed for people who don't really understand ebooks or technical issues. And there's the access to the Amazon store, which includes a lot of free ebooks. (My older daughter has a Kindle, but it's not hooked up to an Amazon account; she can't buy or download Amazon books. Still, she's *constantly* reading it; access to the websites with fiction collections are as good as downloaded books to her.)
Are you familiar with plenty of sources for free ebooks? Some of the best are here at Mobileread; these are hand-formatted by people who know & love ebooks. For others, there's always
Project Gutenberg, and places like
Feedbooks that have creative commons releases as well as public domain books.