Apps for Understanding the Circle of Fifths
Circle Theory
($4.99)
Designed for both iPhone & iPad
Link: http://itunes.apple.com/us/app/circle-theory/id289187333
Circle Theory is a graphical Circle of Fifths identifying relationships between notes, key signatures, intervals, and transposition between keys. An iPad VGA adapter can be used to view the circles on a screen or with a projector.
Quinterval
FREE
Designed for both iPhone & iPad
Link: http://itunes.apple.com/de/app/quinterval/id373810100
Quinterval is an illustrated Circle of Fifths showing major and minor keys and intervals. Keys can be selected by tapping the screen or using the graphical knob. Available in German, English, French and Spanish.