The Halacha requires using a Ke'arah (platter) to serve the various foods for the Misvot of the Seder. While the Ke'arah does not have to be specially designed for the Seder, it is not sufficient to place each item separately in it its own bowl on the table.
Rabbenu Ha'Arizal (Rav Yishak Luria of Safed, 1534-1572) revealed as special order in which to lay out the various foods on the Ke'arah. This can usually be found as an illustration in the beginning of the Hagaddah. Rabbi Mazuz taught a simple way to remember this order, by merely remembering two words: "SeMaH ZeVaHeCHa"-literally meaning, "Be happy with your Korban Pesah." It is an acronym for the order of the various foods starting from the top of the Ke'arah. 'S' is for 'Shalosh"-three, hinting to the three Massot. 'M' is for Maror, and "H" is for "Hazeret"-the endives. That is the first word "SeMaCH." Now, proceeding from right to left: 'Z' is for "Zeroa"-the shank bone. On the left is "Vet" for the "Besa"-egg, on the right bottom is "H" for Haroset and left bottom is the "Kaf" for "Karpas."
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Hacham Bension holds that the measure of a Kezayit (olive's bulk) for the round hand-baked Massot equals 20 grams. Before the Seder, one should weigh his Massot to determine how much of the Masa is a Kesayit. Some people eat the soft Massot which have a different density than the "cracker" Massot. Rabbi Mazuz as well as Hacham Bension and Rabbi Ben Moshe, hold that 35-38 grams of these Massot equal one Kezayit. Even though the Kezayit is a larger amount, this does not create a problem to consume in the requisite time of "Kedeh Ahilat Peras," since it is easier to eat them. Two Kezayits are eaten for Mosi Masa, One for Koreh and one (preferably two) for the Afikoman.
The proper measure of a Kezayit of Maror is 30 grams, although those who are lenient to use 20 grams have upon what to rely, since Maror is M'Drabanan.
