CREATE TABLE "table1_29436238_1" (
  "no_in_series" real,
  "no_in_season" real,
  "title" text,
  "directed_by" text,
  "written_by" text,
  "original_air_date" text,
  "production_code" real
);

Question: How many episodes were written by Gregg Mettler?
SQL: SELECT COUNT("no_in_series") FROM "table1_29436238_1" WHERE "written_by"='Gregg Mettler';

Question: What date did episode 4 in the season originally air?
SQL: SELECT "original_air_date" FROM "table1_29436238_1" WHERE "no_in_season"=4;

Question: What date did "the big giant head returns again (part 1)" originally air?
SQL: SELECT "original_air_date" FROM "table1_29436238_1" WHERE "title"='\"The Big Giant Head Returns Again (Part 1)\"';