Key signatures explained for parents and kids

A key signature is the group of sharps or flats written at the start of each line of music, just after the clef. It tells the player to raise or lower those notes every time they appear, all the way through the piece. One sharp on the F line means every F is F sharp. A key signature also tells you the key, which is the scale the piece is built on.

Why music has key signatures

A piece built on the G major scale uses F sharp in place of F all the way through. Writing a sharp sign in front of every F would clutter the page. The key signature says it once, at the start of each line.

A key signature applies to every note with that letter name, high or low. A sharp on the top F line of the treble staff also changes the F in the bottom space.

Sharps and flats

A sharp raises a note by a half step. On a piano, that is the nearest key to the right, black or white.

A flat lowers a note by a half step, to the nearest key on the left.

A key signature has sharps or flats, never both.

The order never changes

Sharps are always added in the same order: F, C, G, D, A, E, B. A key signature with two sharps has F sharp and C sharp. It cannot have any other two.

Flats are added in the reverse order: B, E, A, D, G, C, F. A key signature with two flats has B flat and E flat.

A phrase helps with the sharps: “Father Charles Goes Down And Ends Battle.” Read it backward for the flats: “Battle Ends And Down Goes Charles’s Father.”

The first keys a student meets

Key signature	Major key	Notes changed
No sharps or flats	C major	None
One sharp	G major	F sharp
Two sharps	D major	F sharp and C sharp
Three sharps	A major	F sharp, C sharp, and G sharp
One flat	F major	B flat
Two flats	B-flat major	B flat and E flat
Three flats	E-flat major	B flat, E flat, and A flat

How to name the key

With sharps. Find the last sharp, the one farthest to the right. The key is the note one half step above it. If the last sharp is F sharp, the key is G major.

With flats. Find the second-to-last flat. That flat is the name of the key. If the flats are B flat and E flat, the key is B-flat major. One flat alone is F major, which a student learns by heart.

With nothing. No sharps and no flats means C major.

Each signature has two keys

Every key signature is shared by one major key and one minor key. The minor key starts three half steps lower. No sharps or flats can mean C major or A minor. One sharp can mean G major or E minor.

To tell which, look at the last note of the piece. In most pieces, it is the home note of the key. Major and minor scales explained covers how the two differ in sound.

Sharps and flats inside the piece

A sharp, flat, or natural written beside a single note is called an accidental. It changes that note for the rest of the bar only. After the bar line, the key signature is back in charge.

A natural sign cancels a sharp or a flat.

Things to do together

Key detective. Open your child’s music book to any piece. Count the sharps or flats and name the key from the chart.

Circle the notes. In a piece with one sharp, find and circle every F. Each one is played as F sharp.

Play the scale. On a piano, play from G up to the next G on white keys only. The seventh note sounds out of place. Now play F sharp in place of F. That is why G major needs one sharp.

Say the order. Chant the order of sharps to a beat, then the order of flats.

Write one. On blank staff paper, draw a treble clef and write the key signature for D major: a sharp on the top F line and a sharp in the C space.

Print and play

The piano keyboard chart helps a child find each sharp and flat on the keys. For the words used here, see the plain glossary of music words. The full guide is music theory for parents.