If your piano is slightly out of tune it does not regester the right note, for instance my piano is out of tune and there is nothing I can do about that, Simply piano made me play Bb for middle C and Db for D. Also, when I was playing, very accented notes, it counted me wrong on the first exercise because it thought I was not playing the notes! They need to make it wear everyone can learn because middle C sounds different on each and every indevidual piano. I used to take piano lessons, I know.