Theory in Practice: Being Flexible on the Gig

I always feel fortunate and grateful for any opportunity to make music. Often you don't know what shape those opportunities may take. This past weekend I was fortunate to be busy with quite a bit of music making. Three gigs in two days can be exhausting and exhilarating at the same time. The thing is, these gigs represented three completely diverse musical environments in terms of venues, musical styles and performance expectations.

• Gig #1: A wedding ceremony recessional and cocktail hour music. 
• Gig #2: Swing dance music for an energetic swing dance society's monthly dance. 
• Gig #3: A church service commemorating the 320th anniversary of a large New England Congregational Church. 

I wanted to focus on gig #3 and one of the practical music theory applications I relied on to get me through the performance of one of the songs.

As we prepared to perform with the church choir, this piece was on my music stand. As I was playing guitar, I was a bit taken aback by the lack of a guitar part... (Full size version)

The expectation was that I play a guitar accompaniment with just this copy of music to use as a guide. 

Here are a couple of the thought processes that informed my playing:

• Knowing this was a simple church hymn, I surmised that the chords would be basic triads or (at most) 7th chords.
• This style also relies more often than not on root-position chords.
• Without a lot of accidentals, I figured the chords were mostly diatonic to the key of G (Than You Circle of 5ths!)
• I quickly scanned the page and started constructing triads or 7th chords out of the stacks of notes.

Bottom line... How do you turn a page of music like the one above into a practical lead sheet?

A practical lead sheet would look something like this:

Let's see how you do with this on the spot musical analysis (Uh Oh, the gig starts in 5 minutes!)