Listening to audio lectures can be a great way to learn new things or to sample subjects to see whether they peak your interest. Here are some of the best free lectures online with very talented teachers whose passion for their subjects will inspire students and whet their appetite for knowledge.

History 7B US History: from Civil War to Present, Jennifer Burns, UC Berkeley

An excellent course on American history by an interesting and engaging lecturer. This lecture would be an excellent supplement to a junior high or high school history class.

Psychology 135 - Social Psychology, Benjamin R. Karney, UCLA

I highly recommend this course for anyone interested in psychology. This course explores how our behavior is influenced by social forces and Professor Karney teaches the subject in a very entertaining and often funny way.

Computer Science E-1: Understanding Computers and the Internet, David Malan, Harvard

Have you ever wondered how computers work? This is an introductionary course that helps build a solid foundation of knowledge about computers and the internet. David Malan explains important basic concepts in a straight forward manner without getting too technical. This lecture would be great for a student interested in computer science or anyone who would like to learn more about computers and the internet.

There are many more great lectures that are publically available by leading schools like MIT, Berkeley, and Harvard that can be browsed at iTunes U.