<p>I'm self-studying it this year. Most people agree that Environmental Science is the easiest AP to self-study. The Smarty Pants guide to Environmental Science seems to be the CC consensus on the best book to use to self-study. I don't know about any online courses for it.</p>
<p>The prereqs for APES at my local high school is the completion (with a B+ or better) of Biology, Chemistry, and Physics or Earth Sciences. I don't think that they're completely necessary, but a solid foundation in each would make life easier. Most of the things you need to know are easy to learn (e.g. the Ideal Gas Law, food chains, etc.).</p>
<p>At my school, it is possible to take AP ES concurrently with chemistry, only having taking biology the year before. So essentially, you start the course having only had biology, and potentially knowing nothing about physics or chemistry, meaning they're probably not very necessary.</p>
<p>We have no pre-requisite course, but biology, admittedly, would help a lot (especially AP's ecology sections).</p>
<p>Um. Well, I took the class until January, then made a 5 with a grand total of six hours of study the day before the test. It's definitely bsable.</p>