As they eagerly bound off the large black steps of the bus wearing matching shirts and name tags, it hits them and their small faces crinkle and they say in unison, "Ewww, what smells?" This is the common first reaction of the thousands of schoolchildren that visit Centennial Farm annually, a four-acre demonstration farm where guided tours give them hands-on, up-close agricultural education.

Since 1989, small children's groups, generally ranging in age from kindergarten to third grade, have had the opportunity to take guided tours of the Farm, which features small and large livestock and growing seasonal crops.

"There are many reasons we offer the tours," said Evy Edelo, agricultural education supervisor. "A few are to expose children to agriculture in a true setting, provide them with an understanding of where their food and fiber come from, and instill an appreciation of the work that farmers do."

Twice a day, five days a week, volunteer docents, known as "Farmers" guide groups of about 18 to 35 students through the rows of crops and past oxen, pigs, calves, sheep, goats and more.

On the guided tours, the Farmers share with the young visitors some basic facts about the various animals and crops. The children learn how many stomachs Lily, the Farm's retired dairy cow, has; how the fluffy coat on the bashful sheep are shaved off, twisted and pulled to make sweaters; how the popular Bill and Bob together are known as "oxen"; and that the Farmers and staff don't really live at the Farm.

Participants of the guided tours also get the opportunity to hold a young chick and learn about the 21-day process of how an egg becomes a chicken. There is also a special milking demonstration and a seed-planting stop where the youngsters get to take home a memory of their visit to the Farm.

Guided tours are offered Monday through Friday at 9 a.m. and 11 a.m. There are a limited number of slots (7 per start time per day) but self-guided dates are available every month for pre-kindergarten school groups, Mommy & Me clubs, and other schools who are unable to book a guided tour.

The Farm's 2005-06 season started in September and ends June 2. The Farm is closed all major holidays and for the Thanksgiving holiday Nov. 21-25, winter break Dec. 19-Jan. 6, and certain events including the OC Fair, Sand Sports Super Show and Pet Expo.

For more information or to make a reservation, visit www.ocfair.com.