FROM a child's perspective -- low to the ground and hemmed in by a jostling crowd -- a visit to the National Gallery of Art's Impressionist show may be more of a turn-off than a turn-on to art. But beginning this weekend the Gallery is offering kids a unique angle on one of the show's most famous painters.

Downstairs in the West Building auditorium, kids six to 12 can meet Edgar Degas in the flesh, at work in his studio on a copy of one of his paintings hanging upstairs in the exhibit.

Degas is really James Heard of the City Literary Institute in London who is reincarnating the painter in twice-daily performances that transport young audiences back to 19th- century Paris and the world of the Impressionist painters.

Not only do the kids get to know Degas during these "Meet the Artist" shows, but they also get a chance to help paint a copy of his "Madame LaLa at the Cirque Fernando" in oils. The painting was obviously chosen to appeal to youngsters. Madame Lala is a circus acrobat suspended from a rope gripped between her teeth, and Degas painted her from an unusual perspective -- from below, just as though he had taken a snapshot from his ringside seat.

This educational entertainment, sponsored by AT&T, has been designed to encourage active interest in the technique of painting. It's part of the Education Department's family program, but the whole concept belongs to Heard.

Since 1980, the 42-year-old Heard has been entertaining young audiences at London's National Gallery with his recreations of Botticelli, Holbein, Gainsborough and Seurat in a series of "Meet the Artist" performances. Degas is his American debut, and it's a juicy role.

The auditorium's lights focus on a stage transformed into a typical 19th-century Parisian studio. Japanese prints line the two-toned gray walls, and a stove and lamp provide a glimmer of warmth and light in a room full of paper, brushes and paints. The canvas sits on its easel waiting to be completed.

Dressed in suit and top hat, Heard enters Degas' studio and begins work. He encourages members of the audience to ask questions and take part in visual experiments. And 10 or so budding artists are invited on stage to help mix pigments and dab on paint. Questions from the floor range from a spontaneous "Why did you paint that person with a big nose?" to the much more teacher-inspired "What artist has influenced you most?"

Heard explains his "trade secrets" in simple lay child's terms, being careful to always stay in character. His seemingly effortless style belies months of research and his penchant for absolute historical accuracy. He spent six months before his Washington tour absorbing the character of Degas, reading anything that could have influenced him or inspired him, from Dante to Zola. And he read Degas' own notebooks and correspondence, consulted 19th-century children's books and explored contemporary inventions and gadgetry. Research into the Franco-Prussian War and the siege of Paris in 1871 led him to a sense of the times in which Degas and other Impressionist painters lived and worked. He even visited the site of the Cirque Fernando near Montmartre where Madame LaLa was the star of the show, but the area had been overrun by strip joints and bars.

Heard also designed his studio set (constructed by Al Campbell, the assistant building superintendent, in the National Gallery's workshops), the lighting and the sound effects. And he created the contemporary posters advertising his "demonstration," the entry tickets and the pamphlet that's handed out at each performance. The pamphlet offers photographs, drawings, contemporary prints and commentary on Degas' work relative to other Impressionist painters. The whole project is a one-man tour-de-force but Heard insists that the concept is not a theatrical one.

He doesn't consider himself an actor, but first and foremost a teacher who interprets art in an unusual way. He doesn't wear make-up and he doesn't use a script because he believes it's important to tailor each enactment to each audience.

Does anything ever go wrong with Heard's enactments?

"Once," he says, "in the middle of a Seurat performance in London, one of the doors of the set accidentally opened to reveal a workman in overalls painting a wall."

The room he was in was actually being refurbished and work was continuing quietly behind the scenes during his show. He quickly recalled that Seurat had painted "The Bathers" (the canvas he was working on) in his studio while some workmen were outside. So he was able to include the working painter in his conversation and the audience didn't know the appearance was unintentional.

"One usually finds things slip into place rather well in the end," says Heard with great equanimity. UP CLOSE AND IN OILS

James Heard's "Meet the Artist: Edgar Degas" is aimed at children six to 12 years old. There are no advance reservations; free tickets will be distributed in the Constitution Avenue lobby a half hour before each performance. Priority will be given to children and their parents. Performances last about 45 minutes, depending on audience participation, and they're given in the National Gallery of Art's West Auditorium, which holds about 150. For more information, call 842-6249 weekdays; 842-6188 weekends. Here's the performance schedule:

FRIDAY -- 10:30. SATURDAY & TUESDAY -- 10:30 and 12:30. SUNDAY & APRIL 6 -- 12:30 and 2:30.