Teaching ABC's with wood and ink

''A for asphalt'' or ''F for fast food'' just wouldn't do for Mary Azarian in her one-room schoolhouse in northern Vermont. Arriving for her first day of teaching several years ago, Miss Azarian says she ''found the large schoolroom entirely bare except for the wooden desks. . . . The need for warmth, light, and color was obvious.''

So the artist picked up her tools, some blocks of wood, and, using the skills she learned studying woodcutting in college, set about carving a decorative teaching aid in the form of alphabet posters. She says she hoped the woodcuts would ''celebrate some of the rural traditions that still are observed in New England today.''

The results, ranging from Apple to Zinnia, included an ''O'' that became an eerie Owl flying at night over fields and farmhouses instead of a swinging Orangutan in a city zoo. Her ''M'' became a stand of Maples at sugaring time - and not the golden arches of a MacDonald's. The ''C''? A Cow being milked with two Cats looking on - and not a shiny, gas-guzzling Car.

Her project, originally aided by a grant from the Vermont Arts Council, later was picked up by the Vermont Board of Education. Sets of her woodcuts were distributed to every elementary school in Vermont.

In 1981, the woodcuts were printed in book form. Demand for ''A Farmer's Alphabet'' is so great, says publisher David R. Godine (Boston), he cannot keep it in print.

Making woodcuts is one of the oldest ways to make a picture. Miss Azarian says after drawing a design on a piece of smooth, straight-grained wood, she uses 12 special Japanese tools to carve out all the areas that are not drawn on. Then the block of wood is inked with a roller, and rice paper is laid on top to pick up the ink.

Despite Miss Azarian's claim that woodcuts as an art form are not very popular today, she seems to have carved a niche for herself as an illustrator of rural Vermont.