Having learned the Grade 2 scales I have tried to understand a bit more about their construction and theory. Dorian on A and G I think I get - as well as understanding that mixolydian on D is built on the major scale of G (5th degree and has an F#). But 5th degree of B major gets me to F as the starting note for this scale - and it has a Bb and Eb - and this doesn't fit with any major scales! (Missing 3 other # to be B maj) Help! Is my understanding of building modal scales all wrong? I have been through a number of texts and sites and am not getting any clearer.