Music Theory for the 21st-Century Classroom

To write an interval above a given note, use the two methods given below.

If you are asked to write a minor sixth above the note $\text{A}$, start with the $\text{A}$ major scale and key signature. In $\text{A}$ major, there is an ${\text{F}}^{♯}$, which is a major sixth above the note $\text{A}$. Therefore, ${\text{F}}^{♮}$ is a minor sixth above $\text{A}$.

Alternatively, you can simply count the number of half steps. If you know there are 8 half steps in a minor sixth, you can count from $\text{A}$ up to $\text{F}$.

Writing small intervals up to a major third below a given note is straightforward using a combination of whole and half steps. However, to write larger intervals below a given note, it is sometimes helpful to invert the interval first (Inversion of Intervals Explained is discussed in the next section).