T.C. Williams High School Orchestra concertmaster Alex Kerr, son of John and Rosita Mang of Peacock Ave., Alexandria, has been awarded the first Young Musicians Fund grant by the Washington Music Ensemble.

Members of the ensemble observed contestants in public performances. Kerr had performed in the Alexandria Waterfront Festival concert. A junior at T.C. Williams, he attends The Juilliard School in New York once a week. Kerr began studying the violin in the fourth grade at Patrick Henry Elementary School in Alexandria, and hopes to be a soloist with a large symphonic orchestra. Alexandria's Teacher Nominee

Flo West of the T.C. Williams High School English Department has been selected as Alexandria's nominee for the Virginia Teacher of the Year Award. Each school system may nominate a teacher for the award, sponsored by the Council of Chief State School Officers, Good Housekeeping magazine and the Encyclopedia Britannica Cos. In December, four national finalists will be chosen from the state winners. A national Teacher of the Year will be named next April at a White House ceremony.

West already has been given an Excellence in Education Award by the Alexandria Chamber of Commerce, and is this year's runner-up for Virginia Speech Teacher of the Year. She is writing a textbook for the English-as-a-second-language speech course that she has developed over the past four years at T.C. Williams, and is also writing a book with eight other Virginia teachers on how to use small groups effectively in education. New Library Volunteer

After 17 years as a rehabilitation teacher for the Virginia Department for the Visually Handicapped, Gerard Arsenault, who is blind, has taken a new job as a volunteer in the Alexandria Library Talking Books Division. The talking books service, sponsored by the Library of Congress, provides book cassettes and disks to the visually and physically handicapped. Arsenault cleans, rewinds, maintains and prepares cassettes for shelving. Scout Leader Recognized

U.S. Army Reserve Maj. Kenneth P. Davis of Phyllis Lane in Alexandria was awarded the Army Achievement Medal from the Department of the Army for outstanding community service with the Boy Scouts.

Davis gave extensive volunteer service to scouting as chairman for youth services at the national jamboree earlier this year. He recruited, organized and trained a staff of 80 adults that supported 30,000 scouts at the jamboree.