user: Question: Who was the director of the episode "Graduation Day: Class of 2105"?
Columns: ['No. in series', 'No. in season', 'Title', 'Directed by', 'Written By', 'Originalairdate', 'TV Broadcast']
Types: ['real', 'real', 'text', 'text', 'text', 'text', 'text']
Sample row: [117.0, 1.0, '"Future Shellshock"', 'Roy Burdine', 'Marty Isenberg', 'July29,2006', 'S06E01']
SQL:

assistant: SELECT "Directed by" FROM "Table" WHERE "Title" = '"Graduation Day: Class of 2105"';