The theory behind singing in harmony
Before you can sing a harmony you have to know which note to aim for. This drill trains that: given a melody note and a key, find the third or sixth above or below it, decide whether it is major or minor, and pick the note that fits the chord under the melody.
Try the notes with your voice in the Sing in Harmony trainer, or write out a whole line with the Harmony Finder. The guided route is the Sing in Harmony program (beta).
Frequently asked questions
How do I find a third above a note in a key?
Count two steps up the scale. In C major from E: F is one, G is two, so the third above E is G. You count the notes of the scale, not the half steps, so the result is sometimes a major and sometimes a minor third.
And a sixth?
Count five steps up the scale. A sixth above a note is the same note name as a third below it, in a higher octave.
How do I know if a third is major or minor?
Count half steps: four is major, three is minor. In a major key the thirds above the 1st, 4th and 5th steps are major, and the others are minor.
Why do the notes of the chord matter?
A harmony note that belongs to the chord underneath sounds settled. A note outside the chord, even one in the key, clashes unless it moves on quickly.