Kathleen Sweeney-Hammond, a chemistry teacher at the Maret School in Washington and a recipient of the 1984 Presidential Award for Excellence in Science and Mathematics Teaching, recommends these science magazines, kits and books for children: MAGAZINES AND KITS

Your Big Backyard, a monthly magazine of wildlife pictures, stories and simple projects for preschoolers. $8.50 a year, National Wildlife Federation, 1412 16th St. NW, Washington, D.C. 20036. (202) 797-6800.

Ranger Rick, a monthly magazine of wildlife pictures and projects for 6-to-12-year-olds, $12 a year, National Wildlife Federation.

National Geographic World, a monthly magazine of science and nature pictures, stories and activities for 8-to-13-year-olds. $9.95 a year, National Geographic Society, 17th and M streets NW, Washington, D.C. 20036. (202) 857-7000.

THINGS of Science, a monthly science kit with instructions and materials on magnetism, fossils, aerodynamics and other topics. For 10-to-16-year-olds, $17.50 a year, THINGS of Science, RD #1, Box 130, Newton, Pa. 18940. BOOKS

Science Experiments You Can Eat, by Vicki Cobb ($4.95, Harper & Row).

Great Perpetual Learning Machine, by Jim Blake and Barbara Ernst ($11.95, Little, Brown).

Adventures With a Microscope, by Richard Headstrom ($12.50, Peter Smith).

Whole Cosmos Catalog of Science Activities for Kids of All Ages, by Joe Abruscato and Jack Hassard ($12.95, Scott, Foresman & Co.).

Safe and Simple Electrical Experiments, by Rudolph F. Graf ($3, Dover).

A sampling of science museums and activities in the Washington area (all free, unless noted):

National Museum of Natural History: Discovery Room (Mon.-Thurs., noon-2:30; Fri.-Sun., 10:30-3:30), an exhibit area where youngsters can touch bugs, shells, animal skins and other specimens. Constitution Ave. at 10th St. NW, Washington, D.C. (202) 357-2700.

National Air and Space Museum: Spaceships and airplanes plus giant-screen films and a Spacearium, which creates the illusion of space travel. Open daily 10-5:30. Independence Ave. at 8th St. SW, Washington. (202) 357-2700.

National Zoological Park: Three hands-on exhibit rooms: HERP lab (reptiles and amphibians, Wed.-Sun., noon-3); Birdlab (eggs, nests, etc.; Fri.-Sun., noon-3); and Zoolab (a little bit of everything, Fri.-Sun.; noon-3). 3000 block of Connecticut Ave. NW, Washington. (202) 673-4717.

National Museum of American History: Giant pendulum plus lots of cars, trains, machines, electricity and other exhibits and demonstrations. Open daily 10-5:30. Constitution Ave., between 12th and 14th streets NW, Washington. (202) 357-2700.

Capital Children's Museum: Hands-on museum with machines and scientific exhibits for children as young as 18 months old. Tues.-Sat., 10-4; Sun., 1-5. 800 Third St. NE, Washington. $2 per person. (202) 543-8600.

NASA/Goddard Visitor Center and Museum: Self-guided tours of rockets, moon rocks, and other artifacts (Wed.-Sun., 10-4); guided tours of the communications and tracking center (Thurs., 2 p.m.); actual launches of model rockets (1st and 3rd Sundays, 1-2 p.m., weather permitting). Soil Conservation Road at Route 193, Greenbelt, Md. (301) 344-8981.

Rock Creek Nature Center: Exhibit area of snakes, insects, etc., plus three self-guided nature trails (Tues.-Sun., 9-5). Weekend planetarium shows (1 p.m. for ages 4 and up, 4 p.m. for ages 7 and up). 5200 Glover Rd. NW, Washington. (202) 426-6829.