Author of this post is Jiří Cvrkal, thanks go his way !
I would like to continue on my post about transpositionIt is again for complete beginners who want to understand those many chords. It is nothing world-shaking, when we start from the basics we find it is actually quite simple.
Let me repeat what tonal key is. We usually say that we play something in C, or in C major, and that means we play in C major tonal key. If we would like to play it higher or lower for easier singing, easier playing, or to adapt to other players, we can use other tonal keys like D major, E major, F major, G major, A major and B major (in Czech notation H major). There are also tonal keys C# (read C sharp) major, D# major, Eb (read E flat) major and other, but we probably won't use those on ukulele, so let's not complicate our life with those yet.
Each tonal key has three basic chords. The main one is called TONIC. We usually start and end the song with it and it also says how the tonal key is named. The next one is called DOMINANT. It is sort of opposite to tonic and some songs use just these two chords. The third chord is SUBDOMINANT, which means lower dominant. As you can find from the table it is located the same distance from tonic like dominant, but in opposite direction. Using these three chords you can play most campfire songs , folk, rock and similar songs. And this is for now all we need to know from the theory.
In practice you can use this tool. If you already have made the strips for transposition, you are half way done. Now just make another strip where you mart the tonic, dominant and subdominant, according to the picture. (Note: the subdominant is shown twice on the strip, just to not make the strip too long.) Working with this tool is simple: set the arrow on tonic to chord, which corresponds to the tonal key. E.g. if you want to play in D tonal key, set it to D, and you directly see where the dominant and subdominant are. Use the same way for other tonal keys too.
As soon as you become friend with the tool, learn those three chords for basic tonal keys (C, D, E, F, G and A major) by memory. This is what every guitarist, ukulelist and every musician knows. But don't hurry. Add next tonal key only after you are sure on the previous one. You will find that each chord has it's name but also it's function for particurat tonal key. E.g. G chord is dominant in C tonal key, but in G tonal key it is tonic, etc. I would like to point out also that the dominant is played often as 7th chord, but you don't have to play it as 7th when starting, it will make no problem. Example again: the dominant in D major tonal key is A or A7.
Next time we will talk about "secondary" chords and later also about minor tonal keys. It won't be anything complicated and there will be a tool again.
At the end here is a link to song Zuzana which uses the three chords and can be transposed, so you can use it to verify this tool works.