CREATE TABLE table_18367694_3 (no_in_season VARCHAR, directed_by VARCHAR)

When joan tewkesbury is the director what is the number in seasons?
SELECT no_in_season FROM table_18367694_3 WHERE directed_by = "Joan Tewkesbury"
SELECT "no_in_season" FROM "table_18367694_3" WHERE "Joan Tewkesbury" = "directed_by"