CREATE TABLE table_13301516_1 (no_in_series VARCHAR, original_air_date VARCHAR)

How many episodes originally aired on April 29, 2008?
SELECT COUNT(no_in_series) FROM table_13301516_1 WHERE original_air_date = "April 29, 2008"
SELECT COUNT("no_in_series") FROM "table_13301516_1" WHERE "April 29, 2008" = "original_air_date"