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ENCINO — "Do you think Israel will trade the Golan Heights for peace?" asks my 16-year-old son, Zack.

He is following the ups and downs of the Israeli-Syrian peace talks with heightened interest — and some self-interest, since he will soon be traveling to Israel.

More significantly, Israel is now not only the historic homeland of the Jews and the modern Zionist miracle. It's also the birthplace and home of Ya'ir Cohen, his 15-year-old Israeli "sibling," who spent three months this fall as a member of our family.

"I'm very protective of my 'falafel,'" Zack adds, using his pet name for Ya'ir, who reciprocates by calling Zack his "hamburger." The boys even, uncannily, resemble each other.

Zack and Ya'ir are participants in the Israel Exchange Program sponsored by Milken Community High School in Los Angeles and Tichon Chadash High School in Tel Aviv. The program, part of the larger Los Angeles-Tel Aviv Partnership 2000, now in its second year, pairs groups of Israeli and American 10th-graders.

From September through November, Ya'ir experienced life in our testosterone-laden American Jewish home, with Zack and his three younger brothers, ages 12, 10 and 8. We introduced him to High Holy Days services at our Reform synagogue, Shabbat dinner, football and chocolate-covered Oreos. We showed him how we retain our Jewish identity in a predominantly Christian society.

In return, Ya'ir helped the three younger boys with their Hebrew homework and basketball shots and taught us that friendship and humor transcend borders and cultural barriers.

In March, Zack, along with the other 17 American students, will fly to Israel to live in their buddies' homes and attend Tichon Chadash High School.

The program seeks to address more than one agenda, according to Yoav Ben-Horin, the director of special programs at Milken.

"These Israeli kids," he explained, "think they are coming to America to forge friendships with their American Jewish counterparts and to live a vida Los Angelena. But actually, they are traveling 6,000 miles to discover what being Jewish means. To discover what being Israeli means."

The Israeli teenagers consider themselves 100 percent Jewish. But, for the most part, they rarely set foot in a synagogue or celebrate Shabbat with a special dinner. On Yom Kippur, many take the opportunity to ride their bikes on the Haifa Highway, which is closed for the day. Here in America, they are afforded their first opportunity to examine the concept of Jewishness in a larger context.

"I am Jewish through osmosis, just by breathing the air in Israel," Ya'ir explained to us. "My whole life is Jewish."

In fact, Ya'ir epitomizes the kind of Jew that the early and truly revolutionary Zionists envisioned: vibrant, self-confident, a fluent Hebrew speaker, far removed from the stereotyped timid, insecure diaspora Jew.

Ya'ir also marks Jewish occasions. He celebrated a bar mitzvah. He keeps kosher. He participates in seders and sukkah-building. And he's active in the Israeli scouts. Ya'ir has a visceral and passionate tie to Israel, to the people and land. Still, he has lost some of the traditional connection to Jewish ritual and religion.

Zack's beliefs exemplify the new American Jewish attitude toward Israel. Early American Zionists — those unwilling to move to Israel — supported the Jewish state financially, morally and politically. They applauded Israel's existence and felt their sense of Jewish pride rekindled. But at the same time they often remained distant from and condescending toward Israel and Israelis.

For Zack, Israelis and Americans are on equal footing. Having spent 11 years in Jewish day school, he has studied Jewish religion, history, language and culture. He has experienced some of the traditional connection to Judaism, the religious significance, but he lacks the intense and intimate connection to the land and the language that Ya'ir embodies.

So, together, these students delve beyond comparisons of falafels vs. hamburgers, of freedom of movement vs. reliance on cars, of secular Judaism vs. Reform and Conservative Judaism. They question what makes a person a Jew: Is it connection to a land, a language or a shared history? Is it adherence to a religion, society, culture or morality?

Zack and Ya'ir, and the other American and Israeli exchange students, who studied, partied and prayed together, traveled and talked incessantly, are busy e-mailing and telephoning. They are exchanging gossip and plans for the next leg of the program. And they are wondering if they will make a last historic visit to the Golan Heights.

In June, when the extended stays and tear-filled farewells have ended and the deep friendship remains, when they have a chance to reflect on this incredible experience, they will begin to understand what it means to be an Israeli Jew and an American Jew.

While they may never ultimately define what makes a Jew, they will understand that their future, and the future of Zionism, is one.