This weekend, melt into summer the way you used to when you were a kid, all sunburnt and sweaty and dripping chocolate on your white shorts. On Saturday, The Lloyd House of the Alexandria Library is holding an ice cream social, with music and lemonade, on its lawn. The same afternoon, McLean is celebrating 70 years of its history with an ice cream social, too.

Admission to the following activities is free unless otherwise noted.

FREDERICK CRAFT FAIR -- Friday through Sunday, 10 to 6, Frederick Fairgrounds, Interstates 70 and 270, Frederick. Dizzie Gillespie performs Saturday and Sunday at noon and 3; more than 350 craft displays, plus ethnic food. $4 for adults, children under 12 free with parent. 301/432-8438.

MILITARY MUSTER -- Saturday, 8 to dusk and Sunday, 8 to 2, Smallwood State Park, four mileswest of Pisgah, off Maryland Route 224. 1776 reenactment. 743-7613.

BEGINNING BIRDING -- Saturday, 9 to 11 a.m., Huntley Meadows Park, Harrison Lane and Lockheed Boulevard, Hybla Valley. Meet at the parking area. Bring waterproof boots, binoculars and field guides. 768-2525.

McLEAN DAY CELEBRATION -- Saturday, 11 to 4, McLean Center, 1236 Ingleside Avenue. An ice-cream social, contests, entertainment, pony rides. 790-9248.

MERCHANT HISTORY -- Saturday, 11 to 5, Torpedo Factory Art Center, Third floor, 105 Union St., Alexandria. "Artifacts, Advertisements and Archaeology," exhibit of the wares of Alexandria plus 201 years of ads from the "Gazette." 703/838-4399.

PYRITE MINE HIKE -- Saturday at noon, Prince William Forest Park headquarters. Hike for three miles to the remnants of a fool's-gold mine. 703/221-2104.

POLICE WEEK EXPOSITION -- Saturday, noon to 5, West Falls Church Metro Station, I-66 and Haycock Road. Displays and demonstrations include child fingerprinting, SWAT vans, helicopters. 241-5066.

ICE CREAM SOCIAL -- Saturday, 2 to 5, Lloyd House, 221 N. Washington St., Alexandria. Ice cream, lemonade and gingerbread cookies; live music. Proceeds go to the Virginia history section of the Alexandria Library. 838-4577 or 836-7590.

DANCEAMERICA! -- Saturday, 6 p.m., Washington Convention Center, 900 Ninth St. NW. High-school student dance marathon for Children's Hospitals. 745-3207.

STAR GAZING -- Saturday, 8:30 to 9:30 p.m., Burke Lake Park Amphitheater, 7315 Ox Rd., Fairfax Station. Slide show led by Geoffrey Chester of NASM. 451-9588.

MINIATURES SHOW AND SALE -- Sunday, 10 to 5, Tysons Corner Holiday Inn, on Rte. 123, McLean. More than 50 craftsmen, with workshops and demonstrations. 978-5353.

GARDENING OPEN HOUSE -- Sunday, 11 to 4, American Horticultural Society, River Farm, off the East Boulevard Drive exit of the GW Memorial Parkway. Bring a picnic lunch. $2 for members, $3 for non-membes, children under 12 free. 768-5700.

COMMUNITY MAY FESTIVAL -- Sunday, 11 to 5, Mount Vernon Hospital, 2501 Parker's Lane, Alexandria. Tour of the hospital, hot air balloon rides, music, food, games. 664-7260.

BELTSVILLE DAY -- Sunday, noon to 6, Beltsville Community Center, 3900 Sellman Rd., Beltsville. Bands, balloon rides, pony rides, crafts, clowns and food. 445-4500.