Read and write rhythm using note and rest values, simple and compound time signatures, beaming, ties and dotted notes, and identify the metre of a passage

What this dot point is asking

SEAB wants you to read and write rhythm accurately: to know the note and rest values, to fill and check bars against a time signature, to use dotted notes, ties and beaming, and to identify whether a passage is in simple or compound time. The central insight is that the time signature is a contract for every bar: the lower number names the beat unit and the upper number says how many fit in a bar, and every bar must add up to exactly that total.

The answer

Note and rest values

Each note value is half the length of the one above it. Taking the crotchet (quarter note) as one beat:

• A semibreve (whole note) lasts four beats.
• A minim (half note) lasts two beats.
• A crotchet (quarter note) lasts one beat.
• A quaver (eighth note) lasts half a beat.
• A semiquaver (sixteenth note) lasts a quarter of a beat.

Every note value has a matching rest of the same length, which is silence rather than sound.

Dotted notes and ties

A dot after a note adds half of that note's value again, so a dotted crotchet lasts one and a half beats (one plus a half). A tie is a curved line joining two notes of the same pitch into one continuous sound, used to carry a note across a bar line or to make a value the basic symbols cannot show.

The time signature

A time signature has two numbers. The lower number names the beat unit (4 means the beat is a crotchet, 8 means the beat is a quaver). The upper number says how many of those units make a bar. So $\frac{3}{4}$ means three crotchet beats per bar, and $\frac{2}{2}$ means two minim beats per bar.

Simple and compound time

The crucial distinction is how the beat divides:

• In simple time each beat divides into two equal halves. Examples: $\frac{2}{4}$, $\frac{3}{4}$, $\frac{4}{4}$.
• In compound time each beat divides into three equal parts, and the beat is a dotted note. Examples: $\frac{6}{8}$ (two dotted-crotchet beats), $\frac{9}{8}$ (three) and $\frac{12}{8}$ (four).

Metre is also described by the number of beats: duple (two), triple (three) or quadruple (four). So $\frac{6}{8}$ is compound duple and $\frac{3}{4}$ is simple triple.

Beaming

Beaming joins quavers and shorter notes with a thick horizontal beam to show the beat groupings clearly. Notes are beamed in beat-sized groups so the eye sees where each beat starts, which is why $\frac{6}{8}$ is beamed in two groups of three rather than three groups of two.

Examples in context

Example 1. A march versus a jig. A military march is usually in simple duple time ($\frac{2}{4}$), with a steady left-right tread and beats dividing in two. A jig is in compound time ($\frac{6}{8}$), with a lilting two-in-a-bar feel and each beat dividing into three. Hearing whether the beat splits in two or three is how you tell them apart in a listening question.

Example 2. Syncopation in popular music. Much popular and dance music places accents off the main beat, tying or stressing the weak parts of the bar to create syncopation. Reading the ties and the beaming on the page shows where the accents have been displaced from the expected beats.

Try this

Q1. State what each number in a time signature tells you, using $\frac{3}{4}$ as your example. [2 marks]

• Cue. The lower number names the beat unit, here a crotchet (4); the upper number gives the beats per bar, here three, so $\frac{3}{4}$ is three crotchet beats per bar.

Q2. Explain how to decide whether a piece is in simple or compound time. [2 marks]

• Cue. Listen to or read how the main beat divides: into two equal parts is simple time, into three equal parts is compound time, where the beat is a dotted note.

Q3. A bar in $\frac{4}{4}$ contains a dotted minim. State how many beats remain and give one way to fill them. [3 marks]

• Cue. A dotted minim is three beats, so one beat remains; fill it with a crotchet, or with two quavers, or with a quaver and a quaver rest.