It would be awesome to have lessons on muted/ghost notes. Muting is talked about briefly, but really we need lesson videos, and SONGS to play with these muted notes. Almost every genre has bass playing with "ghost" notes which are muted notes played for bass and there are a few songs in Yousician with them, but there is no lesson. It seems a huge omission. Lesson and lots of practice songs with muted notes. Once these lessons and songs (at various levels) are there, then any song with muted notes can be played (Premium Plus songs have muted notes [e.g. RHCP and BB King] though there is no Yousician lesson even mentioning "ghost" notes for Bass).