Grade Three Music Theory - Lesson 5: Degrees of the Scale & Tonic Triads (ABRSM)

Suitable for: ABRSM Grade 3 GCSE AP Music Theory Beginners

Degrees of the Scale

The degrees of the scale are numbers given to each note of the scale in order.
The numbers are based on the ascending scale:
degrees-of-scale-c-minor

In a harmonic minor scale, the 7th degree of the scale is always raised by a semitone (half step). In a melodic minor scale, the 6th and 7th degrees of the scale are raised by a semitone in the ascending scale, but no degrees of the scale are changed in the descending scale.

Tonic Triads

The first degree of the scale is also known as the tonic.

A tonic triad is a chord built up from the 1st, 3rd and 5th degrees of the scale.
For example, here is the tonic triad in F minor:
tonic triad f minor
It’s built on the tonic, F, with the 3rd degree of the scale, Ab, and the 5th, C.

Identifying Tonic Triads

You might be asked to identify a tonic triad. What key is this tonic triad?

First, work out the lowest note. The lowest note here is G.

Next, look at the middle note – does it occur in the major or minor form of the scale? The middle note here is Bb. Bb occurs in G minor, but not in G major. Therefore, this chord is the tonic triad in G minor.

If you are not sure whether it's major or minor, you can count the semitones (half steps) from the lowest note to the middle note. If there are 3 semitones, it's minor, if there are 4, it's major. For example, G-Bb is 3 semitones (count G#-A-Bb), and G-B is 4 semitones (count G#-A-Bb-B).

Adding a Clef and Key Signature/Accidentals to Tonic Triads

You might be asked to add a clef and a key signature or accidentals to a tonic triad. Which clef and key signature do we need to add to this tonic triad?
what clef and key signature to add?

To make the lowest note an A, we need to add the treble clef. (If we put a bass clef, the lowest note would be a C.)

The key signature of Ab major has 4 flats, so we need to write in Bb, Eb, Ab and Db, in their correct positions:
tonic triad answer

If you are asked to add accidentals instead of a key signature, start by making a note of what the key signature is (e.g. Bb-Eb-Ab-Db for Ab major), then look at the triad and identify any notes which will need accidentals. In the Ab major triad, the Ab and Eb will need flats next to them, but the C does not need any accidentals.

If you don't have much space to write the accidentals, place the highest accidental close to the note on the stave, then off-set any lower accidentals to the left, so that they have enough room. For example, here is the tonic triad in F# minor, which needs F# and C#. If you write both of them close to the triad, they will overlap and become unreadable, making the A seem to have a sharp as well:

f-sharp-minor-squashed