Music Theory for the 21st-Century Classroom

A major scale contains a specific succession of whole and half steps. It is helpful to think of the pattern as consisting of two tetrachords. (A tetrachord is a four-note scale segment.) The lower tetrachord consists of the pattern whole step, whole step, half step. A whole step joins the lower tetrachord to the upper tetrachord. The upper tetrachord duplicates the pattern in the lower one: whole step, whole step, half step. If we use W for whole step and H for half step, the major scale pattern is W–W–H, Whole–step connection, W–W–H.

All major scales use the notes of the musical alphabet in order; no notes are skipped and no notes occur twice. In the example above, the first four notes are $\text{D}$–$\text{E}$–${\text{F}}^{♯}$–$\text{G}$, not $\text{D}$–$\text{E}$–${\text{G}}^{♭}$–$\text{G}$. In $\text{D}$–$\text{E}$–${\text{G}}^{♭}$–$\text{G}$, $\text{G}$ erroneously occurs twice and the ${\text{F}}^{♯}$ between $\text{E}$ and $\text{G}$ is skipped.