QUOTE(Robodoc @ Sep 13 2007, 11:43 PM)

You can play (and teach and learn) piano on a good keyboard, though the real thing is better. You can't play (or teach or learn) keyboard on a piano.
What a great summary...

I taught keyboard for quite a while, although my piano students outnumbered my keyboard ones by quite a bit. I didn't enjoy it much, and stopped this year when I finally had enough piano pupils to afford it. Here's a few bits and pieces I found:
[Note, other folk may disagree, or have come up with better methods, but anyway...]
1.
In the early stages, keyboard is harder for beginners than piano, not easier.I found this strange, and difficult to explain to parents, but from a pianist's point of view you should understand. Kids beginner books tend to start them off with just a note or two in each hand, then add another, have a page of getting to know that, then add another etc. It's very gradual, and you don't move onto the next bit until you're familiar with the last. Keyboard books tend to dive straight in with a beginner using all five right hand notes (C-G) in the first tune.
2.
Keyboard books sometimes discourage note reading.At least two tutor's I've used in the past made it a habit of writing the note names next to the notes. It would be written by the first of a row of repeated notes, and then by every change. This goes on for a book and a half and then suddenly they stop it, and the pupil's crutch is gone - and you discover that they can't read the music!
3.
Learning keyboard has more stages per piece than piano. Again this is something that affects beginners mostly. I can sit down, look at and play most keyboard music at sight, chords, backing and melody, but beginners don't have that luxury. If you're learning a piano piece from scratch, as a beginner, usually you try both hands seperatly until they're fairly comfortable, then put them together. [So, 3 stages, left, right, together]. With the keyboard though, there's the added complication of the beat, so learning a new tune becomes, right hand, right hand with the beat, left hand chords, left hand chords with the beat, hands together without the beat, and hands together
with the beat...
They might be working on a couple of those at the same time (hands sep. with the beat and together without) and more advanced students may be able to cut some out - say, skip the "together without the beat" stage - but the whole thing is a lot more fiddly. Which means each piece takes that bit longer to learn. Drove me nuts...
4.
The beat itself causes problems. Now, some of this will be no trouble at all for someone who perhaps already learns another instrument, and particularly if that instrument is piano, but for absolute beginners who expect keyboard to be the easy option, the beat is just a nuisance. The tutor books don't give much attention to explaining the concept of the pulse, and it's surprising how many people just can't hear it. So when they put the melody and chords against the beat/style of the machine itself, they tend to just play on at their own pace while the keyboard rattles on itself. Almost any musician listening can find the start of each bar (knew there was a purpose to all that aural...) but beginners really don't understand it, and they're already struggling just with the lengths of notes as it is [since the books tend to introduced quavers and dotted rhythms pretty quickly too].
Anyway, this has degenerated into a bit of a rant, so I think I'll stop. I think many keyboard tutors seem to assume a level of musical ability or knowledge that perhaps just isn't there. I've also had pupils come to me from other teachers/schools who have had lessons for a couple of years and never been taught to use the beat - but then if you're not going to do that, why not just learn the piano...?
Bah humbug...