"The Children of Martha Walter," an exhibit of 37 works by Walter -- known for her American Impressionist style -- that have never been shown before, runs this weekend through November 23 at the Arts Club of Washington, 2017 I Street NW, and benefits the National Center for Missing and Exploited Children; 634-9821; free . . . Pianist Dana Brown performs with the Beethoven Society Pops Orchestra Sunday at 3 at the Capitol Hilton Hotel, 16th and K streets NW; $5; 363-8328. IN MARYLAND

The 34th Washington D.C. International Race, a 11/2-mile race run on grass for a $400,000 purse, is Saturday at Laurel Race Course, Route 198 at U.S. 1 in Laurel. Post time is noon; $3, $5 clubhouse; 725-0400. IN VIRGINIA

There'll be an ARC Record Convention, with everything from rock to oldies, Saturday from 9 to 4:30 at the Holiday Inn Crystal City, 1489 Jefferson Davis Highway, Arlington; $2; 521-1600 . . . The Claude Moore Colonial Farm at Turkey Run hosts its Harvest Celebration Sunday from 1 to 4, a demonstration of family life in the 1770s at harvest time; free hot cider. 6310 Old Gorgetown Pike, McLean; admission is $2, $1 for children under 12; 442-7557.