Blues

The chords in 12 bar blues in C would be:
C C C C    or C7 C7 C7 C7 or C  C   C  C7
F F C C         F7 F7 C7 C7      F   F   C C7
G F C C        G7 F7 C7 C7     G7 F7 C  C

These are the letter names of the notes in each chord
C=C,E,G
C7=C,E,G,B♭
F=F,A,C 
F7=F,A,C, E♭
G=G,B,D
G7=G,B,D,F

The Roman Numerals for the structure of 12 bar blues is:
I   I    I   I
IV IV I   I
V  IV I   I
The technical names for these are:
I = Tonic IV = Sub-dominant V=Dominant

A verse of 12 bar blues has three lines with 4 bars in each line. Lines 1+2 are the same. Line 3 rhymes with the first 2 lines.

Here is an example of 12 bar blues lyrics

Line 1: The first line of the blues is always sung a second time
Line 2: The first line of the blues is always sung a second time
Line 3: So when get to the third line you’ve had to think of a rhyme

Blues keywords

Suspended 4th or 7th = a ½ step lower than the 4th or 7th degree of a major scale (the suspended 7th of C major is B flat)
Boogie-woogie bassline = a bassline which has a dotted rhythm which has the same rhythm as the words boogie-woogie.
Twelve bar blues = a common pattern of blues which has 12 bars in each verse and 3 lines in each verse

History of Blues

Nobody knows when blues originated, but it is thought to be at some point in the 19th century.
The main reason we don’t know when it originated is that it developed over a long period of time.
Blues is from America and west Africa.

From the 1600’s slavery was common. The slaves were mostly black Americans and Africans, but convicts were also sold into slavery.
They worked on the plantations in their countries to grow crops that could be grown in England.

While they were working they would sing call and response songs which were the earliest form of blues.
After the abolition of slavery blues music developed with access to more instruments.
The blues lyrics talked about the experiences the slaves had making them sad and soulful.

Instruments used in blues

Guitar
Piano
Harmonica
Bass guitar
Drums
Saxophone
Vocals
Trumpet
Trombone