For the alfred's all in one books 1 2 and 3 there is the

lesson theory technic
and
lesson theory solo

books, what is the difference between the "solo" and the "technic" part and which version is better?

and for book 2 the lesson theory technic book seems to be missing from amazon.com, or does it not exist?

Just a misunderstanding I think. They called level one Lesson-Theory-Technic (why not Technique?) and levels two and three are both called Lesson-Theory-Solo.

But they are just levels one, two and three of the series.

then why not name them all the same title, instead of some being technic and others being solo. that doesn't make sense.

Alfred and their parent company probably know way more about marketing and selling music books than all of us combined.

Here's the second volume of the Alfred Adult All-In-One books. The back cover from the "Look Inside" feature shows the three book covers. It distinguishes between technic in book one and solos in books 2 & 3 as contents, it seems, rather than as a subtitle.

http://www.amazon.com/Alfreds-Course-All...red+adult+piano

Great question! If you look through all three of Alfred's Basic Adult All-in-One books, you'll see a few technical exercises, but these are mainly for finger strength and coordination. If a student needs more technical help, we have supplemental books for that. The "Solo" designation just means that there are more songs included in the All-in-One format. You are right that the covers should be more consistent, though. I'll bring it up to our editors. "Technic" is an old term that was common in teachers' vocabulary in past years. Please email us or give us a call for more help! We love talking to students and teachers! keyboard@alfred.com or (818) 892-2452. Keep makin' sweet music! :-)