2. What Mitzvos were given at Marah?
3. How many years were B'nei Yisroel in Mitzrayim?
4. Who authored the first Brocha in Birkas Hamazon?
5. Why is there a Minhag to leave food out for birds on Shabbos Shirah?
Answers:
1. According to the Ramban, the conclusion of Shiras Hayam is Shmos 15:18. The Ibn Ezra says that it is 15:19.
2. Shabbos, Parah Adumah, and civil laws (Rashi Shmos 15:25).
3. 210 years.
4. Moshe Rabbeinu wrote it when the Mon began to fall.
5. Doson and Aviram scattered Mon in the fields on Shabbos to try and discredit Moshe who said Mon would not fall on Shabbos. The birds ate up this Mon to defeat Doson and Aviram's plot. (Nitei Gavriel in the name of R' Meir of Premishlan).