quiz before lesson?
Why is the new information not posted at the top of the pages instead of the bottom? This is like being tested on new information before it's even taught. I could scroll down and read it first of course but I need to know it's there - and that it changes as I progress.
I think you misinterpret what Duolingo is. The “quiz” is actually the lesson, and the information below is supplementary notes. The basic idea is that you learn the language by translating individual sentences, and deriving the underlying rules on your own. And if you're stuck, the notes are here to help you figure out what's wrong. More or less. Do read the notes before doing the lessons though, I'm not saying you shouldn't.
Not all skills have notes. It differs from course to course too: for example, the Polish course doesn't have any notes whatsoever past lesson 8 (just imagine that for a moment). If Duo taught swimming, you would not have any explanations and were just thrown into water right away.
It is additional information. Not every lesson has this additional information. If you encounter difficulties with some task you can read the discussion in the task (the "discuss sentence" button) for clarifying. Also you can ask your question there.