Musictheory.net

http://www.musictheory.net/index.html

An interactive series of activities designed as tutorials to help with basic music concepts. Topics of related interest here include intervals, scales, chords and key signatures.

The Circle of Fifths

http://cnx.org/content/m10865/latest/

This site provides a handy introduction to the relation of the circle of fifths to key signatures and offers interactive exercises.

The Tonal Centre

http://ds.dial.pipex.com/andymilne/

The Tonal Centre introduces the elements of harmony through the principle of tonality. A bit more advanced content wise than the other sites, you can find information on basic chord construction, extensions, and a number of progressions and forms. The site includes a useful and detailed treatment of modulation.

Questions

1			What is the difference between a harmonic and melodic minor scale?
2			Define the term "enharmonic."
3			What is the function of the "circle of fifths", and how can you use it to identify the elements of a key?
4			What is meant by the term "relative minor" key, and, how do you go about finding out what it is.
5			Describe the two fundamental forms of modulation.