Can baby boys or girls be identified by their smiles? Is chewing gum that contains sugar digested more rapidly than that which does not? Which vegetable and fruit dyes color fabric best? Can dogs respond to shapes on cards as visual commands?

These were a few of the myriad of hypotheses that seventh- and eighth-grade students tackled with their projects last Saturday at the Diocesan Science Fair. Held at Bishop O’Connell High School in Arlington, the fair drew about 265 colorful and ingenious projects from 28 participating schools, each of which could enter 10 apiece. A Home Schooling Science Fair occurred two weeks earlier at St. Louis School in Alexandria.

Project ideas often originated from everyday experiences. Melissa Richards, a seventh-grader at All Saints School in Manassas, was walking a female infant during babysitting last summer when someone went by and exclaimed "What a cute baby boy!"

This exchange was the impetus for her project, "After Awhile Can You Tell by the Smile?" in which she investigated "Is gender identification of infants by their smiles an inherited ability specific to men or women learned by exposure to infants?"

Richards explained that through her Internet research she learned that scientists have proven that baby boys smile with their mouths more wide open and girls with theirs more closed. The photos and data she had displayed in her behavioral and social sciences category project illustrated this point.

In the same category, seventh-grader Tom Decker of Queen of Apostles School in Alexandria had been assisted by his dog, Trevor. He said the canine helped him on "Can Dogs Respond to Shapes (as visual commands)?" by "being the science project subject and participating in the trials."

When Decker began his research on Dec. 12, Trevor "was scared of the signs and ran back under the bed." By the end of the timeframe, on Jan. 2, the dog "responded correctly three times to the visual command." The project won an honorable mention.

Seventh-grader Catherine DeMarino of Corpus Christi School in Falls Church investigated "Gum Digestion," which won second place in the biochemistry category. She was drawn to this because of her little brother, Michael, 18 months old, who "likes sugar and the colors of gum." Even though he does not yet chew the substance, "I figured he’d like gum when he got older," she said.

In botany, eighth-grader Andrew Spurr of St. Timothy School in Chantilly, sat by his several-inch tall flower examples which illustrated that "Water: Too Much of Good Thing Can Be Bad," which won second place in the category. His project was subtitled: "Sequel to Fertilizer: Too Much of Good Thing Can Be Bad," which was his last year’s entry.

For her Chemistry category project seventh-grader Chelsea Cayer of Holy Cross Academy in Fredericksburg examined "Creative Vegetable and Fruit Dyes." Her display showed that after boiling the foods and using their liquid to color different fabrics, grapes were the strongest hue, with beets coming in second.