Among the episodes aired on April of 2009, how many episodes won an award?
aired on refers to air_date, April refers to SUBSTR(air_date, 6, 2) = '04'; 2009 refers to SUBSTR (air_date, 0, 5) = '2009'
SELECT COUNT(T1.episode_id) FROM Award AS T1 INNER JOIN Episode AS T2 ON T1.episode_id = T2.episode_id WHERE SUBSTR(T1.year, 1, 4) = '2009' AND T2.air_date LIKE '2009-04%';