The keyboard can be used to work on many skills and objectives, and many children are very motivated to play it. Unfortunately many parents feel uncomfortable trying to teach any skills on the keyboard because they never learned to play themselves. The next few posts will be dedicated to keyboard activities to try with your children- even if you're not a musician!
I would recommend locating a keyboard that has at least 61 keys. The keyboard I have used and like the most in my practice is the Yamaha YPT-300AD Full-Size 61-Key Touch-Sensitive Keyboard. Unfortunately, I think it's been discontinued and I can't find it anywhere. Yamaha has another model that looks pretty close, the Yamaha YPT-320 61 Key Personal Keyboard with AC Adapter, Deluxe Keyboard Stand and Professional Headphones . I found it sold in a bundle with a keyboard stand and AC adapter through Amazon. There are also several other Yamaha keyboards available that would should work very well. I would caution against the lighted keyboards as I think they can be overstimulating for some children.
Here is a color chart that I use for the keyboard. The green "C" should be placed on the C in the middle of the keyboard - middle C. The re B, A, and G should go below the Green Tabbed Middle C.
You can make a chart like this on your computer or with colored paper and tape it to your keyboard. Warning - tape, if left on the keys too long can give your keys a tacky feel. For songs to play with your colors, check out Piano by Color on the Activity Download tab above.