BOB ABERNETHY, anchor: Every year as Passover approaches, Jewish children learn the significance of unleavened bread -- matzah -- eaten at each Passover seder. We found Jewish kids learning to make matzah at the Temple Sha'arey Shalom School in Springfield, New Jersey. The chief baker is Rabbi Zalman Grossbaum.

Rabbi ZALMAN GROSSBAUM (Chabad-Lubavitch, New Jersey): The matzah, because of its symbolism, is definitely the icon of Passover, and eating it is a biblical obligation. When we start the matzah bakery, we first introduce the kids to the story of Passover.

(Telling Joke to Students at Sha'arey Shalom Jewish School, Springfield, NJ): "Knock, knock." Pharaoh says, "Who's there?" He says, "Moses." He says, "Moses who?" He says, "I don't have time for knock, knock jokes." "I have something very important to tell you." He says, "What? What did you want to tell me?" He says, "I came to tell you to let my people ..."

STUDENTS (In Unison): "Go!"

Then we start the actual baking process. First the children separate the kernels from the chaff.

(To Students): Extra care has to be made to make sure that it stays perfectly dry.

(Singing): Bang, bang, bang. Give a heavy blow!

Then they grind the kernels into flour. And although matzah is very simple -- it is water and flour -- there's extra care taken that until the moment that the water and flour mix in the bakery and they're ready to make the dough, [the water and flour] cannot come in contact with each other at all. So, they bring the flour into the flour booth, the water in the water booth.

(To Classroom): Water. Some mayim. The most important job in a matzah bakery is the timer. From the moment that it mixes, we only have 18 minutes until it starts to rise. Any moment over the 18 minutes, not only is it not matzah, it's actually what we would call "chametz," chametz being leavened bread, which would be forbidden to eat on Passover.