A good director is capable of deriving keys from the tuning fork. But doing so isn’t always easy. From the A of the tuning fork you would like to jump to the new root at once. However, not every interval is that easy to find. An ascending second or fourth is doable. But a sixth or a tritone, can be really hard to find.
Some keys are straightforward. The key of A (either major or minor) is rather easy. The root is the note A of the tuning fork. It is a matter of singing the major or minor scale from there. For the keys that lie a second from A – G, G
@ and B (major or minor) – there is only one obvious way to derive them. Just go from the a directly to the new root.
But if the root lies further from A, it gets more difficult to deduced the key. In many cases there are several methods to choose from. For example, the D can be derived in two ways. From the low A you might take a fourth up. Or from the high A you might take a fifth down:
In the same way, you may derive the key of C (major or minor) going up or going down. From the low A you can think a minor third up. The disadvantage here is that you actually derived the key A-minor, before thinking of C. The other method is taking a major sixth down from the high A, but that is not an easy interval to pinpoint. However, there is a third possible method! From the high A you might take a major second down to G. From this note, you can take a fifth down. Because the note G is in the key of C (either major or minor), it is a valuable note to have derived on your way down to C:
In my work as a professor, I often come across students who derive C (major or minor) in the following way. First, from the high A they sing a fifth down to D. Next, they go down a major second to c. In my view, this is not the best way to go about. On the way down, you actually derive the key of D. Your mind has to let go of this key, in order the think of the key of C. Thus, this method is going through an extra key, and this will increase the risk of mistakes and being out of tune:
For the rest of the keys, the same principles apply. We’ll go through them quickly. The key of C
# (major or minor) may be derived through the note G-sharp. Rather not go up a major third from the low A, because at that moment you tend to hear the faulty key A-major. The key of E
@ (major or minor) may be derived through the note B-flat. The key of E (major or minor) may be derived either directly from the note A or through B.
The key of F-major is easy, going down a major third from the note A. However, F-minor is really hard. First, you have to derive F and then you should quickly ‘forget’ the A in order to get to A-flat. Similar difficulties arise when you have to get to F
Rule of thumb
In short: try to make a small step, going from the A of your tuning fork, to either the root or the fifth of the new key. Try to avoid going through another key than the one you want to derive, because it will take you extra effort to let go of it.