Especially for K-12 teachers, check this baby out.  The National Science Digital Library has Science Literacy Maps online.  For a bunch of different topics (Math, Technology, Physics, Nature of Science) you can click to get a concept map of a set of topics.  In physics, for example, you can click on waves to see a map of all the concepts related to waves.  Even better – there is a link within each section to see a list of student misconceptions (with references) related to those topics.