The two notation systems most commonly used today are the Helmholtz pitch notation system and the scientific pitch notation system. As shown in the table above, they both include several octaves, each starting from C rather than A. The reason is that the most commonly used scale in Western music is the major scale, and the sequence C–D–E–F–G–A–B–C (the C major scale) is the simplest example of a major scale. Indeed, it is the only major scale that can be obtained using natural notes (the white keys on the piano keyboard) and is typically the first musical scale taught in music schools.