CREATE TABLE table_228973_9 (no_in_series VARCHAR2, original_air_date VARCHAR2)

If the original air date is April 1, 2003, what number in the series is this episode?
SELECT no_in_series FROM table_228973_9 WHERE original_air_date = "April 1, 2003"
SELECT "no_in_series" FROM "table_228973_9" WHERE "April 1, 2003" = "original_air_date"