They’re short. Predictable. Easy to play and dot the musical landscape like coloured marbles! What makes the lowly pentascale so popular and fitting?
The pentascale, derived from the Greek, pente, meaning five, is a 5-consecutive-note scale starting on the tonic (first note) of any major or minor scale. It’s basically the first 5 notes of any key signature.
As a piano student, your first encounter with pentascales will likely be when first learning to play piano. You might even learn it at your very first lesson, as anyone can play five consecutive notes in a row, especially if they’re all on white keys! For example, your teacher may assign the all-white-key C major pentascale for homework as a context in which to drill proper physical approach at the piano. Your teacher may also assign the G major, A minor or D minor pentascales, as these also occur on white keys only.
Drilling pentascales provides an easy and melodic context in which to practice moving fingers independently with proper form and various types of touch such as detached, legato and staccato. Since C major, G major, A minor and D minor pentascales are all comprised of five consecutive white keys, it’s easy to learn all four of them in one shot! Simply navigate to the next tonic note and play all five fingers in a row! This is why they’re also called 5-finger scales!
Naturally, most students are in a hurry to progress from these seemingly baby scales to full-blown one-octave scales, simply called “scales”, as this enables use of an entire key signature. But there is great advantage in mastering pentascale technique, as our fingers learn to become agile and expressive.
Plus, they’re so melodic and catchy! Listen to a few for yourself:
But what makes them so? Is it just coincidence? Why does a 6 or 7-consecutive-note scale sound not have the same ear-pleasing quality?
Once again, it has to do with the music sound wave itself! Remember in the third instalment of the Journey in the Ear series we learned that all 3 notes of the corresponding major triad chord are present in the sound wave of every note of music whenever you strike a note on a musical instrument. When you strike a C on the piano or on a guitar or a flute, for example, the sound wave contains all 3 notes of the the C major chord - C E G - also known as scale degrees 1, 3 and 5 (first, third and fifth notes)
Remember that we also learned that the strongest overtones, representing the tonic and the dominant (5th note of any major or minor scale) notes, are inherently arranged in such a way within the sound wave itself that they lead back and forth to each other in the following order: C to G to C
A pentascale naturally follows along this pattern of tonic-dominant-tonic. We strike the tonic, and our ear hears the strong dominant overtone; we ascend to the dominant, and our ear is prepared for the descent back to the tonic.
Adding to this pleasant musical relationship is the third note of the pentascale, which, in the case of the C major pentascale, is E. Remember that E is part of the C major triad and is also present in the sound wave itself as a significant overtone. So when we play the C major pentascale we are basically outlining the C major triad and moving towards the E both, ascending and descending. The D leads to E and the F leads back to E. It’s perfectly balanced melodically!
This is why the 6 and 7-note consecutive scales did not sound so good. These push past the dominant pull of the G as an end point, floundering above it without heeding the call to climb to the upper tonic and creating a wayward-sounding tension that is unbalanced, muddies the outlining of the major triad and fails to bring the ear to a satisfying conclusion.
Note how this differs from the pleasing journey of the C minor pentascale, even though the E is now flat (C D E flat F G) and doesn’t belong to the C sound wave:
Even though the ear is not expecting the E flat, creating a somewhat dissonant sound or departure from the norm, striking an E flat produces a strong overtone G that corresponds with the G’s in the C sound wave, strengthening the acoustic and melodic bond of the five notes in the minor pentascale while heeding the pleasing tonic-dominant-tonic pattern produced by the C sound wave.
Who could’ve imagined there was so much going on behind the scenes in the seemingly mundane playground of the pentascale! I'll never look at them, or rather hear them, the same from now on!