Body and Brain Connection

The achievement description on this can be a little misleading, especially once you have played the game for a little bit. To unlock Intermediate and Advanced levels, you have to score a C or better in the previous difficulty level, leading you to believe that scoring below a C may not be considered "completing a level".

But, fear not! All you have to do is unlock every level (all Intermediate and Advanced levels) and play each one regardless of how well you score on the Advanced levels. I have several D's and E's on my Advanced scoreboard and was able to unlock the achievement.

To see your scores and to see which levels you have played and unlocked, go to "My Data" at the Main Menu, then select "Stats". This will show you a chart of your progress for every category and level.

Hope this helps!:)