The Sefer HaChinuch lists as Mitzvah 21 the requirement that woman are included in the Torah requirement - the D’Oraisa of Sipur Yitzias Mitzrayim. They must say the Haggadah at the Seder on Pesach.
The Minchas Chinuch and others wonder at this since it is a Mitzvas Aseh SheHaZman Gramah - a positive and time bound commandment – from which women are exempt. Why does the Chinuch therefore list it as a Torah requirement for women?
One cannot answer the usual ‘Af Hein Hayu B’Oso HNes’ – ‘they too were involved in the miracle’. This is the reason given as to why women are required to light the Chanukah Menorah (either through her own lighting or through others.) That explanation is only given for rabbinic enactments. Chazal included women in time bound enactments that they experienced too. It is not used to include women when the Torah exempts them. So the question remains - why are women required to participate in Mitzvah of Sipur Yitzias Mitzrayim?
The answer can be found in the Sefer Kehilas Yaakov.
There is another positive Mitzvah D'Oraisa that is time bound which women are required to observe on Pesach – that of eating Matzah. The reason they are required to do so is explained by the Gemarah in Pesachim (43b) . There is a comparison to the Lav – the negative commandment - of not eating Chametz. ‘Lo Sochel Alav Chametz Shivas Yomim’ – ‘Do not eat Chametz for seven days’.
The Gemarah then states the following principle: Kol SheYeshna B’Baal Tochal Chametz – Yeshna B’Kum Ochal Matzos. Anyone that is required to refrain from eating Chametz – is required to eat Matzah. When an ASeh (positive commandment) is connected to a Lav (negative commandment) then it loses its exemption status and women are therefore required to participate in it the same as men. So in the case of Chametz and Matzah women are required to refrain from Chametz and required to eat Matzah
What does this have to do with Sipur Yitzias Mitzrayim - which is fulfilled by saying the Hagaddah? The Gemarah in Pesachim (115b) provides us with an answer. One of the reasons that Matzah is called Lechem Oni is that it is ‘bread’ upon which many things are answered. The questions begin with the Mah Nishtana - and the rest of the Hagadah basically answers these question via the recounting the Exodus. That ties eating Matzah to Sipur Yetzias Mitzrayim. One is required to say the Hagadah upon the Matzah. Since women are required to eat Matzah, they are therefore required to do so via ‘answering’ over it through the Hagaddah – making Sipur Yetzias Mitrayim a D’Oriasa requirement too.
* Taken from Torah L’Daas
It should be noted that the Sefer Moadim U’Zmanim suggests that when one uncovers the Matzah before saying the Hagadah, one should expose the broken piece in order to fulfill the second reason given for calling Matzah Lechem Oni - bread which is eaten by poor people who usually eat broken rather than whole pieces.