user: Question: What is the average of the Series #s that were directed by Matthew Penn?
Columns: ['Series #', 'Season #', 'Title', 'Directed by', 'Original air date', 'Production code']
Types: ['real', 'real', 'text', 'text', 'text', 'text']
Sample row: [53.0, 1.0, '"A Time of Faith (Part 1)"', 'Frederick K. Keller', 'August 29, 1996', 'K1501']
SQL:

assistant: SELECT AVG("Series #") FROM "Table" WHERE "Directed by" = 'Matthew Penn';