Simple!By Rabbi Jack Abramowitz
G-d told Moshe that every first-born of the Jews, whether man or animal, is dedicated to Him. (Clearly, this is in exchange for the fact that they were spared the effects of the tenth plague in Egypt. The first-born sons would have had the priestly duties that ended up going to the Tribe of Levi, if not for later developments.)
Moshe reminded the people about the festival of Passover, which would be kept every spring after they entered the land of Israel. When they keep this holiday and all its laws, they should explain that it is because of what G-d did for them when they left Egypt. (Verse 8 includes part of the explanation given the both the wicked son and the one who doesn’t know how to ask, in the Haggadah.) These words were also to be included in tefillin (phylacteries in English, but really, who uses that word?), a mitzvah that will be discussed more fully in parshas Va’eschanan.
When they enter the land, every first-born male of the animals are to be consecrated to G-d. A donkey, which is not kosher, must be exchanged for a sheep. If they failed to do this, the donkey’s neck would have to be severed. A first-born son would be redeemed for five silver shekels. (This is the Pidyon HaBen ceremony, observed to this day.) If questioned by one’s child, the response is that it is because G-d spared us when He killed the first-born males of Egypt. (The answer given in verse 14 includes the response given the Haggadah’s “simple” son; this was also to be included in tefillin.)