If you remember your music history, you will recall that beginning around the 10th century, an existing melody, often a Gregorian chant, was written into one voice of a contrapuntal vocal composition, and then the other voices were composed around it. This chant or anchoring melody was eventually called the cactus firms. The technique was especially popular in the 13th and 14th centuries, including the Notre Dame School. Although this technique was used as a compositional device, it is also useful as a grounding for improvisation. Indeed, before the 15th century, music theorists made little distinction between improvised and notated composition.
With all of this in mind, let us consider the middle school general music class. My students always enjoy drumming, but usually end up either playing the same old rhythm patterns they hear over and over again in popular music, or they try to play so many things at once that it all comes out too noisy with little intent or musicality. Limiting the number of students who play at once helps, but creates other challenges, especially what those non-performing students will be doing while their classmates are drumming. Body percussion, dance/movement, or writing critiques are all possible, and I have used all of these with success. But there is a way to get everyone involved drumming without the problems of a percussive free for all.
Using a rhythmic cantus firmus makes it possible for many more students to drum at once without much loss in musicality. Here’s how I do this. When the students enter the room, an eighth measure rhythm is notated on the board. The rhythm is fairly simple, containing only quarter notes and rests, and paired eighth notes. I ask who can clap the rhythm, and I call on several students to do so, and then have the class clap it in unison. Next, I demonstrate how to clap the music in canon, with a small group of the students who are most confident clapping in unison, while I clap one measure behind. I then divide the class into two, having each half clap one measure apart, while I play a third canon part on a soft drum. This sets up small groups work in which the students will practice clapping the rhythm as a three-part round. I go around to each group and offer assistance until each group has succeeded.
I review (or if you haven’t taught it before, introduce) the concept of complementary rhythms, and point out the complementary rhythms the students just clapped as they performed the canon. With this knowledge in place, the groups of three now operate with one student clapping the notated rhythm (the cantus firmus) while the other two students improvise complementary rhythms to each other and to the cantus firmus. It is important that the cantus firmus and the improvised parts all have some rests, so that there are “windows” in which the others can insert a complementary rhythm. If the students find a way to insert their favorite hip-hop beat, then fine; at least they will do so thoughtfully, understanding how it complements the other parts. Once students realize that the best way for them to be heard is playing in someone else’s silence, they begin looking for those rests, and leaving those rests for each other. There is a point at which they realize that following the “rules” of maintaining the cantus firmus and of complementary rhythms really does result in better sounding music, more enjoyable music making, and avoids the situation of creating too much noise wherein everyone is fighting to be heard, and no one is really enjoying the music.
The same basic plan can be extended to melodic improvisation as well. We all know the utility of the pentatonic scale in teaching improvisation. In moveable do solfege, the major pentatonic scale consists of do re mi so la, and the minor monatomic (la based) consists of la do re mi so. Because of the absence of fa and ti, it is difficult to go to far astray harmonically. If you pick a pentatonic melody as the cantus firmus, then students will be able to improvise freely, concentrating on complementary rhythm and now also complementary melodic contour. I like to use Amazing Grace. The Christian connection is not an issue in my school, and because I am only using the melody and not singing the words, there is probably nothing to object to in using it for most of you. Most of my students know the melody, which makes it enjoyable, and makes the learning of it quicker.
To proceed, as before have the class learn the melody that will be the cantus firmus. I like to use Orff barred instruments, but you could use keyboards, recorders, boom whackers, or band instruments; use whatever is available. Once the students can play the melody, have them find all of the half notes. These will be the “windows” into which the improvisors will place complementary quarter notes. It works well to have students grouped in pairs, with one student playing the melody and the other student placing a patsch on each complementary quarter note. Once that is accomplished, the improvisor transfers the patch to a barred instrument (or other instrument if used), trying various combinations of pitches. The melody is written in such a way that the improvisor will play two quarter notes on beats one and two, and, at least for now, rest on beat three. All that is being improvised at this point are the pitches selected for each quarter note. Once the improvisor has successfully accomplished this, the two students in each pair swap roles, and the process begins again. After that, the improvisor can add a quarter note on some of the third beats, if desired.
If you were to take a class this far, it would be a good lesson on using complementary rhythms to improvise with pitches. The students will have a performance finished, and will feel good about what they have accomplished. To take it further, they could regroup into threes, and have the third member improvise an accompanying rhythm part, perhaps on a shaker or giro. Another direction would be to provide each student with a transcription of the cantus firmus with a second staff blank, and have students transcribe their improvisation. I find that when the students can see the distribution of rhythms in a score which visually represents their complementary nature, it reinforces the concept of complementary rhythms, and it also allows them to realize their use of contrary and parallel motion.