What means Prolongation?

A prolongation progression really just prolongs an underlying tonal center.

For instance, in a basic idea, it is common to use a prolongation progression. The following progressions would be considered prolongation:

I – V – I

I(ped.) – IV – I
—————–

I – ii – V – I

These are all considered prolongations of the I chord. You can change the chords, but the focal point is still the I chord. The same could be done with dominant progressions, which tend to be found in contrasting middle sections of Small Ternary Form.

For instance, this would be considered a dominant prolongation. Even though you use a I chord, it is in 2nd inversion, so it doesn’t feel like you’ve really moved back to that chord as a focal point.
V7 – I⁶/₄ – V7 – I⁶/₄ – V7/ii – ii – V7/V – V7

A progression like this:
I – IV – V/V – vi

Could in one sense be considered tonic prolongation, because I and vi are both tonic function, although it is a stretch. I would say this is not a tonic prolongation progression.

Thank you very much for the detailed answer Jon, i think i get it now. Can i ask you for another Thing? Where can i find the Exercises for the 201 course ( Musescore files etc) In the Workbook 201 you mention that the exercice pages can befound below the Video lessons but i cant find them. You also mention that the exercises could be done in the pdf workbook, but it seems the Content can not be edited. Hope you can explain,thanks again and best regards ,Nik
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Thank you very much for the detailed answer Jon, i think i get it now. Can i ask you for another Thing? Where can i find the Exercises for the 201 course ( Musescore files etc) In the Workbook 201 you mention that the exercice pages can befound below the Video lessons but i cant find them. You also mention that the exercises could be done in the pdf workbook, but it seems the Content can not be edited. Hope you can explain,thanks again and best regards ,Nik
be