Laurie Lederman, age 13, of Staten Island, N.Y., for her question:

WHICH IS THE LARGEST AND SMALLEST DOG?

Winning small dog honors is the Chihuahua. This tiny dog stands only five inches tall and weighs between one and six pounds.

The Irish wolfhound is the tallest of all dogs, measuring almost three feet high at the shoulders. He usually weighs in at between 105 and 140 pounds.

Heaviest of all dogs is the St. Bernard. Although his average  weight is about 175, some of these big dogs can weigh over 200 pounds.

The American Kennel Club recognizes 121 breeds and varieties of purebreds. A purebred is a dog whose father and mother belong to the same breed. When the ancestors of a purebred are known and registered by a breed club, the dog has a pedigree.