Often times, especially at the high-school level, teachers will encounter students enrolling in general music classes just because there was "nothing else available". The environments in these classes can be pretty mixed and matched. You may have students who are familiar with performing and/or reading notation, and you might have students who just want to hide in the back of the classroom with their arms folded across their chests because Woodshop was all filled out when they registered for classes this semester. In these cases, you may have a class with a wider range of overall assets and abilities. This means you have to find something that everyone is capable of doing that is simple enough so students without a strong musical background feel comfortable doing it and something that won't bore those in the class who are already well acquainted with music. Of course teaching musical history is always an option for these courses. And world drumming can also be fun a accessible to everybody, but this is where technology can really come into play. Not all students can easily match pitch or automatically know how to play an instrument, but most students are capable of using computers. So, for general music classes with diverse ranges of musical ability, you can let them play around with music software.
Exploring concepts in music doesn't need to require performance experience or even literacy in musical notation. Music is first and foremost a kind of language and a kind of feeling and if you can't get students engaged in analyzing Bach chorales, you can at least let them explore different musical tools and resources found on the internet. There are several different resources that students of all different skill-levels can use to explore music. Many people are already aware of software like Garage Band and Audacity, but if you search the web, there are so many cool sites out there that can let students explore the world of composition by way of manipulating tonality, meter and style with just the touch of a button. this kind of music exploration allows students to discover how different elements of music fit together and lets them create something in the process. Music is something that people can create and play, and sometimes an entire lesson of just creating and playing music can be beneficial to an education in music.
Some fun sites to share with students:
http://www.incredibox.com/
http://www.seaquence.org/
