Hi,
The song of the week is Shortnin' Bread in the key of G.

Form
Shortnin' Bread is a two-part fiddle tune.  Each part is 4 measures long, and - as is typical for fiddle tunes - is repeated before going on to the next part.  This form (2 parts each repeated) is called AABB.  'A' stands for 'A-Part', i.e., first part, and 'B' stands for 'B-Part', i.e., second part.

Progression
The chord progression for Shortnin' Bread (both parts have the same progression) is typical for fiddle tunes that have 4 measure parts.  The progression is:
1  1  1  5/1

That is, 3 measures of the 1 chord, followed by half a measure of the 5 chord, followed by half a measure of the 1 chord. 
In the key of G: 1 = G; 5 = D.

Melody
The melody of the tune consists of, in ascending order of pitch, the notes GABDEG. This set of notes is called the G major pentatonic scale, and is one of the most common scales used in bluegrass and old-time music. (Compare this with the set of notes used to play the melody for a previous song of the week 'My Home's Across The Blue Ridge Mountains': in ascending order of pitch, DEGABD. Same notes, same letter names (G's, A's, B,s D's, E's), but a different range: D to D rather than G to G.

Recordings
You may notice in listening to the Flatt and Scruggs youtube link below that both the banjo and the fiddle breaks do not stick all that closely to the melody. (In the attachments, the melody given for Shortnin' Bread is the melody as it would be sung, albeit in a rhythmically simpler form that does not account for every sung syllable.)  All the notes are there, however (GABDEG), but the fiddle and the banjo take liberties with the order in which these notes get played.  For instance, taking the first measure of the A-Part, and ignoring the 'filler' notes, the melody being played by the banjo is GDED instead of GEDE. 

Flatt and Scruggs (live) - Shortnin' Bread in the key of G, tune starts at 0:49
https://www.youtube.com/watch?v=0FgpQyk5ibw

Notice that the AABB form is altered the second time through it.  Scruggs plays four B Parts back to back, the first two of which are a variation on his basic B Part.

For another take on the melody of Shortnin' Bread, here is a youtube link of the old-time string band 'The Freight Hoppers' playing Shortnin' Bread (key of A.) In the old-time tradition, all the lead instruments in the band (in this case fiddle and clawhammer banjo) are playing their 'breaks' together at the same time, instead of taking turns.
https://www.youtube.com/watch?v=gfb_LddQ738

AABB Form Tunes
Like almost every other traditional old-time, bluegrass, Irish, or Scottish AABB fiddle tune, the two parts of the tune are differentiated from each other primarily by the fact that one part starts with a higher note than what the other part starts with, and by the fact that the part that starts with the higher note tend to have a melody that is overall higher in pitch - in some cases only slightly higher on average, in other cases, significantly higher on average - than what the other part does.  

In old time and bluegrass fiddle tunes, the higher of the two parts is sometimes the A Part (i.e., the part that gets played first) - this is the case with Cripple Creek and Old Joe Clark - while other times it is the B-Part that is the higher of the two parts (e.g., Soldier's Joy, Boil The Cabbage Down, Buffalo Gals, and the vast majority of Irish fiddle tunes). 

Shortnin' Bread may be played either way, but I have given the higher of the two parts as the 'A-Part' in the attached melody sheets, since that is how I am most used to hearing it played, and it is the way I always play it when I am the one who calls and kicks it off at a jam. (Angeline The Baker is another jam-favorite fiddle tune which can be started with either its high part or its low part.) However, if someone else kicks off Shortnin' Bread at a jam, and they start with the low part instead of the high part, then I follow their lead and play my breaks the same way as they did: low part first, then high part. For, it is the person who kicks the tune off who determines which part is the A-Part and which part is the B-Part.

Also, like many other AABB fiddle tunes, both parts end the same way. (on the melody sheets attached here, notice that the last measure of the B-Part is identical with the last measure of the A-Part) and the two halves of the A-Part begin the same way (notice that measure 3 of the A-Part is the same as measure 1 of the A-Part), and the two halves of the B-Part also begin the same way (notice that measure 3 of the B-Part is the same as measure 1 of the B-Part.

8 Potato Intro
The most effective way to kick-off most AABB fiddle tunes at a jam is not by playing a pickup measure consisting of three quarter notes to lead into your intro break, but is by droning in a straight but rhythmic manner the root note of the key that the tune is in (often together with another one of the notes that also belong to the 1 chord) for four measures to lead into your intro break.This is called in bluegrass and old-time circles the '8 Potato Intro'. 

In the attachments, I have included a sheet that shows good ways to play on fiddle, mandolin, guitar, and banjo, an 8 Potato Intro for the key of G. I have also included on the sheet, a simpler (unfortunately, also less effective when both are played correctly) way to play this type of intro on each of these instruments for those who are new to playing this type of intro, and may have difficulty playing the more developed forms of the 8 Potato Intros with the right feel and with rock-solid timing, since playing with the right 'feel' and timing are crucial to making the 8 Potato Intro an effective jam tool. If anything at all goes wrong with the timing or feel of the Intro or with the transition from the Intro into the Intro Break, the whole purpose for using it is thereby defeated.

Keys
Since Shortnin' Bread has been played just as often at the Beginner Bluegrass Jam in the key of A as it has been in the key of G, I have included in the attachments melody sheets for fiddle and mandolin written in A (in addition to the ones written in G), so that one can easily compare the notes used to play the melody in G with the corresponding notes used to play the melody in A.

The notes used to play Shortnin' Bread in G (from lowest to highest): 
G,   A,   B,   D,   E,  G
The corresponding notes for playing Shortnin' Bread in A:                  
 A,   B,   C#, E,   F#, A
    
Happy Pickin',
Jason

The song of the week is Shortnin' Bread in the key of G.

Shortnin' Bread is a two-part fiddle tune.  Each part is 4 measures long, and - as is typical for fiddle tunes - is repeated before going on to the next part.  This form (2 parts each repeated) is called AABB.  'A' stands for 'A-Part', i.e., first part, and 'B' stands for 'B-Part', i.e., second part.

The chord progression for Shortnin' Bread (both parts have the same progression) is typical for fiddle tunes that have 4 measure parts.  The progression is:

1  1  1  5/1

That is, 3 measures of the 1 chord, followed by half a measureof the 5 chord, followed by half a measure of the 1 chord. 

In the key of G: 1 = G; 5 = D.

The melody of the tune consists of, in ascending order of pitch, the notes GABDEG. This set of notes is called the G major pentatonic scale, and is one of the most common scales used in bluegrass and old-time music. (Compare this with the set of notes used to play the melody for the previous song of the week 'My Home's Across The Blue Ridge Mountains': in ascending order of pitch, DEGABD. Same notes, same letter names (G's, A's, B,s D's, E's), but a different range: D to D rather than G to G.

Like almost every other traditional old-time, bluegrass, Irish, or Scottish AABB fiddle tune, the two parts of the tune are differentiated from each other primarily by the fact that one part starts with a higher note than what the other part starts with, and by the fact that the part that starts with the higher note tend to have a melody that is overall higher in pitch - in some cases only slightly higher on average, in other cases, significantly higher on average - than what the other part does.  In old time and bluegrass fiddle tunes, the higher of the two parts is sometimes the A Part (i.e., the part that gets played first) - this is the case with Cripple Creek and Old Joe Clark - while other times it is the B-Part that is the higher of the two parts (e.g., Soldier's Joy, Boil The Cabbage Down, Buffalo Gals, and the vast majority of Irish fiddle tunes). Shortnin' Bread can be - and has been played at the jam - either way, but I have given the higher of the two parts as the 'A-Part' in the attached melody sheets, since that is how I am most used to hearing it played, and it is the way I always play it when I am the one who calls and kicks it off at a jam. (Angeline The Baker is another jam-favorite fiddle tune which can be started with either its high part or its low part.) However, if someone else kicks off Shortnin' Bread at a jam, and they start with the low part instead of the high part, then I follow their lead and play my breaks the same way as they did: low part first, then high part. For, it is the person who kicks the tune off who determines which part is the A-Part and which part is the B-Part.

Also, like many other AABB fiddle tunes, both parts end the same way. (on the melody sheets attached here, notice that the last measure of the B-Part is identical with the last measure of the A-Part) and the two halves of the A-Part begin the same way (notice that measure 3 of the A-Part is the same as measure 1 of the A-Part), and the two halves of the B-Part also begin the same way (notice that measure 3 of the B-Part is the same as measure 1 of the B-Part.

Besides these commonplace repetitions within fiddle tunes, there are even more points of similarity within the parts of Shortnin' Bread than what is frequently encountered in fiddle tunes.  Notice that the 2nd measure of the A-Part is almost identical to the 1st and 3rd measures of the A-Part.  Notice that the 2nd measure of the B-Part is identical to the 1st and 3rd measures of the B-Part.  Finally, notice that the only difference between the 1st (or 3rd) measure of the B-Part and the 1st (or 3rd) measure of A-Part is which octave the G note is played in that starts the measure.  There is, indeed, very little in Shortnin' Bread to learn or to memorize, for the tune is about as repetitious as what a fiddle tune can be, while still having well-defined parts.

You may notice in listening to the Flatt and Scruggs youtube link below that both the banjo and the fiddle breaks do not stick all that closely to the melody. (In the attachments, the melody given for Shortnin' Bread is the melody as it would be sung, albeit in a rhythmically simpler form that does not account for every sung syllable.)  All the notes are there, however (GABDEG), but the fiddle and the banjo take liberties with the order in which these notes get played.  For instance, taking the first measure of the A-Part, and ignoring the 'filler' notes, the melody being played by the banjo is GDED instead of GEDE. 

Flatt and Scruggs (live) - Shortnin' Bread in the key of G, tune starts at 0:49
https://www.youtube.com/watch?v=0FgpQyk5ibw

Notice that the AABB form is altered the second time through it.  Scruggs plays four B Parts back to back, the first two of which are a variation on his basic B Part.

The most effective way to kick-off most AABB fiddle tunes at a jam is not by playing a pickup measure consisting of three quarter notes to lead into your intro break, but is by droning in a straight but rhythmic manner the root note of the key that the tune is in (often together with another one of the notes that also belong to the 1 chord) for four measures to lead into your intro break.This is called in bluegrass and old-time circles the '8 Potato Intro'. In the attachments, I have included a sheet that shows good ways to play on fiddle, mandolin, guitar, and banjo, an 8 Potato Intro for the key of G. I have also included on the sheet, a simpler (unfortunately, also less effective when both are played correctly) way to play this type of intro on each of these instruments for those who are new to playing this type of intro, and may have difficulty playing the more developed forms of the 8 Potato Intros with the right feel and with rock-solid timing, since playing with the right 'feel' and timing are crucial to making the 8 Potato Intro an effective jam tool. If anything at all goes wrong with the timing or feel of the Intro or with the transition from the Intro into the Intro Break, the whole purpose for using it is thereby defeated.

For another take on the melody of Shortnin' Bread, here is a youtube link of the old-time string band 'The Freight Hoppers' playing Shortnin' Bread (key of A.) In the old-time tradition, all the lead instruments in the band (in this case fiddle and clawhammer banjo) are playing their 'breaks' together at the same time, instead of taking turns.

https://www.youtube.com/watch?v=A00SDXFgxn4

While most fiddle tunes have only one standard key in which they are played (e.g., Soldier's Joy - D, Old Joe Clark - A: it is a good idea to get on the habit of thinking of the key as though it were part of the title of the tune), some have 2 or even 3 or 4 different keys traditionally associated with them. This is especially true of those fiddle tunes, like Shortnin' Bread, that have especially simple melodies. It would not be odd for Shortnin' Bread to be called at a jam in any of the 4 most fiddle-friendly keys: G, A, C, or D. Other tunes like this include: Buffalo Gals (usually G or A though, rather than C or D: but at the old-time jam on Mondays at Pengilly's it often gets played in E: it is usually a sung version that is done there; otherwise 'E' would be an unlikely key for it to be played in at that jam), Liza Jane (G, A, or D), Golden Slippers (G, A, or D), and Miss McLeod's Reel (G or A).  

Since Shortnin' Bread has been played twice at the Beginner Bluegrass Jam in the key of A within the last month, I thought it would be a good idea to include in the attachments melody sheets for fiddle and mandolin written in A (in addition to the ones written in G), so that one can easily compare the notes used to play the melody in G with the corresponding notes used to play the melody in A. This ties in well with the last 2 teaching segments at the Beginner Jam (see below for a summary of these), and it is useful for fiddle and mandolin players to know the relationships involved between the keys of G and A, since there are other songs besides Shortnin' Bread that will tend to show up in both G and A at the jam, depending on who calls them, and in which part of the evening they get called: e.g., Nine Pound Hammer, Buffalo Gals, and Mama Don't Allow.

The notes used to play Shortnin' Bread in G (from lowest to highest): G,   A,   B,   D,   E,  G
The corresponding notes for playing Shortnin' Bread in A:                   A,   B,   C#, E,   F#,
                                                                                                                        do,  re,  mi, sol,  la,  do