Many well-structured astronomy courses are available online.  Some courses are free, and in some cases courses can be taken for college credit.  Courses accessed via the links below offer a range of astronomical topics, and require a range of preparation, from none to various levels of math proficiency:

Free Intro Astronomy Class 2013 - The Planetary Society

Astronomy for Beginners - U. of AZ - 77 lectures

Education Portal:  Sources for Free Astronomy Education

Free astronomy classes & lesson plans - Mankato Homeschooling

Starship Asterisk* Classroom: Introductory Astronomy - 25 lectures

Astronomy Courses - Academic Earth