In this age of dance consciousness, one would think that a movie about one of the great ballet institutions of the world would excite enough public attention to warrant an intelligent, fairly high-level film treatment. "The Children of Theatre Street," which opens today at the K-B Cerberus, both prods and frustrates these hopes.

On the whole, the picture is a grievously missed opportunity for an exploration of Russian ballet training that won't be soon or easily attempted a second time.

The commercially produced, 90-minute feature begins by holding out onscreen narration by Princess Grace of Monaco as box-office bait. One infers that the filmmakers proceeded on the premise that a straightforward picture about ballet education would hardly clear its production costs, and that it was therefore necessary to gild the lily in various ways.

In any case, the movie treads an uneasy course between sentimentality, travelogue platitudes and documentary enlightenment, the last of which almost gets lost in the shuffle.

In spite of itself, "The Children of Theatre Street" still contains enough material that is rare and interesting to remain a must for dance devotees. The broader public the picture seeks, however, is more apt to be bored than entranced by the treacly style and fractured contents of the film.

The Vaganova Choreographic Institute of Leningrad, formerly the Imperial School of Ballet, is widely regarded as the Oxford of classical dancing, a standard-setting academy of the art and science of ballet, founded in 1738 and the purveyor of vaunted pedagogical traditions ever since.

As an incubator for ballet notables, it has an unparalleled track record, numbering among its graduates Vaslav Nijinsky, Anna Pavlova, Tamara Karsavina, Michel Fokine, George Balanchine, Rudolf Nureyev, Natalia Makarova and Mikhail Baryshnikov.

Though Russian authorities cooperated in the making of the film, there was apparently quite a flap when the moviemakers insisted on pointing out in the narration that portraits of the latter three dancers - defectors all - had been removed from the school's walls.

Though the Vaganova school is the ostensible subject of the film, it is amazing how little of the actual schooling we get to see - how the classes are structured and the syllabus arranged, what teaching methods are used and standards of excellence employed, how the Vaganova school differs from other ballet conservatories.

True, one is given glimpses of the entrance auditions, of classes at various levels, of preparations for a graduation recital and the recital itself, as well as intermittent excerpts from performances. But this is all minced in with shots of scenic Leningrad, dormitory pillow fights, picnicking and the like, and the dance photography is often half-baked. Unfortunately, the film rarely rises above its worst feature, the syrupy narration.