A certain amount of clowning is expected from 22 third-graders at the end of a Friday afternoon. But give them plastic aprons, rolling pins, white paper hats, and an unlimited supply of flour — and the circus really begins.

"We look like sailors going to the open sea on matzah," declared third-grader Elie Sherman, turning his hat sideways to look like a sailor's cap.

This led to cries of "Hi ho matzah!" among a handful of children before Rabbi Moishe Pinson brought everyone's attention back to the matter at hand.

The matter at hand was matzah.

Third-grade students at Brandeis Hillel Day School in San Rafael were working March 22 at America's first traveling matzah bakery.

Though the Model Matzah Bakery of San Francisco has brought children to its bakery for more than 20 years to see how matzahs get made, it had never brought the bakery to the kids.

"This is the first time they've been able to compact the whole experience," said Rabbi Meyer Berkowitz, one of three bakers who set up the ad hoc bakery.

To begin, Berkowitz, Pinson and baker Chesky Malamud carried in a portable oven and set up two makeshift booths in teacher Marav Alterman's classroom. The booths represented the separate compartments in which, at a traditional matzah factory, flour and water are kept before mixing.

Pinson told his young charges that matzah baking had to be a tight operation. From the moment the group began adding the water to the flour, they had only 18 minutes to knead the dough, roll it out and bake it.

If they did not meet their deadline, the dough could rise, a definite taboo when making matzah, Pinson told the class.

In that case, their matzah would become chametz — a leavened product.

Student Michele Lansing stood in the area set aside for working with the flour, while Jordan Goldklang stood a few feet away with a cup of water.

As the class yelled the Hebrew words for water (mayim) and flour (kemach), Lansing and Goldklang brought the two ingredients together, and Malamud, the baker, kneaded the mixture into dough.

Then every child took a small piece of dough, dipped it in flour, rolled it out flat on their classroom desks and — to further prevent it from rising — perforated it with plastic forks. The pads of dough that students carried to the oven on their rolling sticks varied from wide and thin to small and lopsided.

A project of the 250-year-old international congregation Chabad Lubavich, the Model Matzah Bakery shows how the sacred traditions of baking matzah have been kept for thousands of years, said Yosef Lubavitch, assistant to Rabbi Yosef Langer, the director of Chabad in San Francisco.

Matzah has been baked the same way since Exodus, whether during enslavement in Babylon, persecution under the Spanish Inquisition, or incarceration in concentration camps during the Holocaust, Lubavich said.

The matzah the kids were making wasn't kosher for Passover, however. For one, at a matzah factory, the flour and the water for Passover matzah are kept in separate rooms before they are mixed — not just in separate areas. For another, the surfaces in the classroom had not been properly inspected for cleanliness and the absence of bread crumbs.

The children were told they would have to wait until after the weekend to see the results of their experiment. At the first presentation of the traveling matzah bakery, the oven had taken longer than planned to reach 700 degrees. So the matzahs didn't get done in time for the children to take them home.

How did the kids think the matzahs would turn out?

"I hope not burnt," said student Erin Moss. "Anything but burnt."

In Lansing's opinion, the matzahs would come out all right. "Very holey," she predicted.