I've taught a few in music classes, not piano though.
Some were quiet. One was easily upset.
I did kindergarten and first grade material them, focused a lot of the beat and having fun with the music. They enjoyed it. I would say that group was one of the best groups I've worked with.
Resources?
Try searching for teaching elementary music to learners with special needs. Something along those lines.
They did not always sing and could not always tap the beat.
They are all different though, just like people in general.
I found them much more open to new music. They did not have any preconvieved idea that "classical music is boring." They pretty much enjoyed anything music. Anything. Play a chord and it was the greatest thing in the world.
Ability-wise, generally behind grade level. Reading ability was a big issue -- just reading words. I don't think I did much with music notation. But you never know. I did have one student who did far, far better than the everyday kids -- because she always tried and gave it her all. As a result, she did well. She memorized everything though.
MENC has some materials. "Spotlight on Making Music with Special Learners" is one of their booklets. Teaching Music magazine had an issue focusing on it -- "Ideas for Teaching Special Learners," and I'm sure it's in othe music magazines. Music Educators Journal is another one.
Not that that stuff really helps much though. You can probably google or find a wiki page that tells the same stuff -- for free.
As far as music goes, I think about the pre-music classes. Those early music classes. Or more if they can handle it. I did a lot more tailoring with the one student I had like that for private lessons. She memorized everything. I made tapes for her to work with at home. The lesson was more like guided practice. "This is what we're working on. Do this. Watch me. Now you." "This is the tape. Let's listen through it and work along with it." I don't know how much she really practiced, but there was definite progress. Selection of music wasn't a big issue. I made sure it was always fun though. I considered enjoyment and making music to be above understanding and building a foundation of music reading skills.
If I had another student like that, I would talk to the parents. Find out as much as you can so you can go into the first lesson with something for them that's appropriate. Sometimes the parents can help. Sometimes the parents have special needs too, so you can't ask them to help a lot.
Those tapes were a must though. I remember that. And having a set way of doing things.
Teaching students with special needs gave me a different angle on teaching. It was interesting, esp with the one that outdid the "normal" kids who weren't trying.
And then on the business side, it was another student willing to pay. Money. And I added that to my teaching credentials -- "I successfully taught students with special needs." Hoo-wah.
It's just like beginning teaching. Dive in and figure things out. The parents may have ideas too.
Topic: Down's Syndrome