Two young violinists made promising solo debuts with the National Symphony Orchestra last night, and four other players of high school age sat in as members of the orchestra under the baton of Fabio Mechetti. It was a "Meet the Orchestra" concert -- low-priced, designed mainly for students and fairly informal, with Mechetti discussing each work before it was played.

In the first movement of Mendelssohn's Violin Concerto, 17-year-old violinist Alexander Kerr gave a fluent, poised performance showing expert control of his instrument and knowledge of the music.

Yuki MacQueen, also 17, played the Introduction and Rondo Capriccioso of Saint-Sae ns, music that makes varied and stringent technical demands. She plays very impressively, with deep, polished tone and dazzling digital dexterity.

Her bravura technique earned her a standing ovation from the young audience, and it was indeed impressive, but one never had the feeling that she was pushing herself to her limit, throwing caution to the wind. Caution may be a good idea in a debut performance like this, but somehow one doesn't expect it in a player that young.

The four temporary orchestra players, members of the orchestra's Youth Fellowship Program who were chosen by audition, were violinists Allison Bailey and Jennifer Memoli of Woodbridge High School, bassoonist Roberta Holtz of Sherwood High School and cellist Eve Miller of Chantilly High School.

The program, including such classical Top 40 items as Bernstein's "Candide" Overture, Barber's Adagio for Strings and Tchaikovsky's "Romeo and Juliet," was calculated to lure the young audience members back for more concerts.