This week's shiurim are sponsored by Valerie Adler in honor of her girlfriends who have been learning and sharing this journey - Sherry Begner, Kay Wineberger, Eti Kornbluth, Lisa Baratz and her daughter Anoushka Adler. Today's shiur is dedicated by Judy Shapiro for the 13th yahrzeit of my beloved father, Albert Tychman, z"l. And by Deborah Kotz in memory of her grandmother, Frieda bat Yosef z"l on her yahrzeit and remembering how much she inspired her students. May her neshama have an aliyah. And by Lesley Nadel in memory of her late sister Ruth Lewis, Rachel bat Berel Halevy of blessed memory whose yahrzeit is today and in recognition of her husband Don who has now completed the entire Shas cycle and begins today his second cycle of Daf Yomi. One needs to check for chametz on the fourteenth of Nissan at night. Why? One does not need to check a place where there is never chametz. The mishna uses the word "light" to denote night when stating when the check (bedika) should be done. The gemara brings two different opinions about the word "light" - does it mean day or night? Several sources are brought to question each of the opinions.