The following is an outline of the 12th chapter of Sh'mot and the difficulty that emerges based on the outline. This is in response to RS's post on Lashon Limudim.
Title: Tzivui Hashem to Moshe as Preparation for Makkat B'chorot
A)1-2 - Mitzvat Kidush HaChodesh
B)3-14 - Mitzvot Chag HaPesach
6 - Sh'chita
7 - L'kicha and N'tinat HaDam
12-13 Tachlit of Korban
14 Zikaron L'dorot
C)15-20 - Mitzvot Chametz U'Matza
15 7 day Matza no Chametz
16 Yom Tov
17A Sh'mira of Matzot
17B-20 Sh'mira L'dorot of Chametz U'Matza
Difficulty - It would seem that the Mitzvot of Chametz U'Matza were for future generations not those who were leaving Mitzrayim. Why is this section placed here? Additionally why is the Mitzva of Rosh Chodesh placed here? It seems the only necessary preparation of B'nei Yisrael was the Korban Pesach. In fact, in 21-28 when Moshe speaks to the Ziknei Yisrael he only instructs them concerning the Korban Pesach. It would seem that the presentation of mitzvot to Moshe must be different from the presentation to the z'kainim. These three mitzvot: Rosh Chodesh, Pesach and Matza/Chametz form one complete system. I need time to contemplate this further.