Magnificent Mangroves. Search for crabs, spiders, snails, owls and other critters in the mangroves and create a nature journal at this program for children 7-11. Reservations are required at least three days in advance. 11-12:30 p.m. Gumbo Limbo Nature Center, 1801 N. Ocean Blvd, Boca Raton. 561-544-8615. Members, $7; Nonmembers, $10. Eco Explorers: Dip-Netting. The day off from school is a great opportunity for children 8-12 to come find out what is living in the center's ponds by "dip-netting" and looking at the findings with magnifying glasses and microscopes. Be sure to wear water shoes or shoes that can get wet and dirty. Registration is required. 2 p.m. Daggerwing Nature Center, 11200 Park Access Road, Boca Raton. 561-629-8760. $4. Holiday Tree Lighting Ceremony. Thousands of miniature lights will appear throughout the city and on a 47-foot Christmas tree as the mayor officially sets off Boca Raton's holiday season. There will be photos with Mr. and Mrs. Santa, rides, face painting, arts and crafts, food, a holiday stage show, piles of snow and entertainment by Boca Raton Community High School's band and other musical groups. 5-8 p.m. Mizner Park, 327 Plaza Real, Boca Raton. 561-393-7827 or miznerpark.com. Free. Cook-A-Book. An interactive cooking and reading program, featuring a book discussion about "Homer Price" by Robert McCloskey, for children in third through sixth grades. 4-5 p.m. Conference 111, Davie/Cooper City Branch Library, 4600 SW 82nd Ave., Davie. Call 954-680-0050. Free. Math and Logic Class. This fun class for ages 6-11 provides an opportunity