Can anyone good at them please give me some advice? I've just started on this topic and sometimes I'm not quite sure when to use which type of cadences.

I use imperfect cadences when the rthymn doesn't repeat itself eg. bar 1-2 is not the same as bar 3-4. Sometimes I have difficulty choosing which progression I should use out of the 3 types. Is it related to what notes are used in the treble stave?

I use perfect cadences when the rthymn repeats eg. bar 1-2 is the same as bar 3-4.

I don't know when to use perfect and when to use plagal.

Cadences with three chords, what I normally do is use a imperfect, then perfect eg. IV-V-I. Is that correct?

Perfect cadence are used normally at the end of the piece to create a sense of completion...
perfect candence is V-I

Imperfect cadence are used at the end of phrase, before another new phrase emerge...
imperfect candence includes I-V, ii-V, IV-V, vi-V

Plagal cadence (if i'm not wrong), can be used at anywhere in the piece
plagal cadence: V-vi


ShArOn

Hi xiaoken

Cadences can be related to rhythm, but it is best to see what the actual pitch of the notes given are. At grade 5 you only need to know I, ii, IV and V. I get pupils to first of all work out what the key is, then to write down the 4 possible chords of that key. Perhaps it is G major. In that case they would write

I G B D
ii A C E
IV C E G
V D F# A

You then look at the notes that have been given to see which chord fits in to which beat. Remember you can have passing notes in the given passage. Incidentally a plagal cadence is IV-I, interrupted (not needed at this grade) is V-vi. A perfect cadence can happen in the middle of an extract and likewise an imperfect one can happen at the end.

Hope this helps. Fire away if you have anymore questions.

Thank you all for your replies. I'm beginning to understand better.

One question though. How do you pick which imperfect cadence, out of the three, to use? Is there any tell-tale signs that the question is lookig for a particular imperfect cadence?

The melody dicatates the chords you choose. If the notes are part of the supertonic chord you would use that for example.

What if the melody is only 1 note? for example, key of C major, and the treble stave is C note then a B note. In the case of the imperfect cadence, I would pick V for the B note, but the preceding note, either I or IV has C in the chords. Do I just choose either one or does only one of them fit the bill?

Ah, I see! Either would be okay, though I would perhaps favour I-V in that instance. Of course it depends on what the chord was before the first chord of the cadence.

What do you mean?

Sorry if I'm asking too much.

If the chord before the 2 chords of the cadence was a IV, I'd certainly go for I-V. At Grade 5 you sometimes get two chords to suggest and sometimes three. The best plan is to make sure that you always end with a I or a V and that you never get two consecutive chords with the same number.