Keys

Lesson 8 of 8 · ~6 min · Interactive

The final piece of the puzzle. When a song is built from one scale, we say it’s in the key of that scale - “in C major,” “in A minor.” The key tells you the song’s home base and exactly which sharps or flats to expect along the way.

1.What is a key?

In Lesson 7 you built G major and discovered it needs F♯. A song in the key of G major uses those seven notes: every F in the song is F♯, and G is home. The key is the scale’s notes plus that feeling of home - melodies wander, build tension, and resolve back to the tonic.

2.Key signatures

Writing a ♯ before every single F in a G-major song would be exhausting. So composers declare it once: sharps or flats written at the start of each staff line, right after the clef, called the key signature. One glance and you know the key - and which notes to alter for the rest of the piece.

3.The circle of fifths

Here’s the map every musician eventually memorizes. Go clockwise from C, a perfect fifth at a time, and each key adds one sharp. Go counter-clockwise and each key adds one flat. Twelve steps later you’re back home. Tap any key to hear its tonic chord and see its signature:

4.Practice: know your keys

Last quiz of the course! The circle above is your cheat sheet.