Kindle seems a sturdy device, but be careful. I put mine in an excellent leather holder - it holds it at a nice angle, you can read hands free and it folds flat. Reaching over something I leaned on the kindle, in its protective holder, with my elbow. Click. The screen was damaged instantly and beyond repair. No warranty. Amazon are replacing it for the reduced price of £50 delivered with their supersaver, and I can't complain at that - electrical repair shops commonly charge £30 just to look at something, and this would have needed a new screen. But I've seen postings on the internet here from people whose kindles have broken after being dropped or squashed in a suitcase - schools might need to think about this before buying Kindles for pupils. I don't know if Sony's ebook is any more sturdy, but I'd check it out.
Do not leave Kindle on a flat surface - anyone leaning on it is liable to break it. Always stand it up. We'll see how long my new one lasts. As I finish typing this, I notice that I have put the Kindle face up, in front of my keyboard, exactly where I broke it the last time. I'm not hopeful.