Watch the The 5 Major Scale Shapes & the 5 Caged Shapes online guitar lesson by Rob Garland from Melodic Soloing: Major Scale

By relating the 5 CAGED chord shapes to the 5 major scale shapes (and also the 5 pentatonic shapes), the fretboard really opens up.

Working through the CAGED system playing a C chord in different positions and playing the corresponding major scale shape, which is always the same in every key.