National Collection of Fine Arts, 8th and G Streets NW. Open daily, 10 a.m. to 5:30 p.m. Free. 628-4422.

Museums understand. They know that winter vacation not only leaves the children's activities right back in the hands of their parents, but unlike summer vacation, leaves them indoors with little chance to burn off all that childish energy. The National Collection of Fine Arts, at least, has scheduled for this holiday season two exhibits which should appeal to children as well as adults. One, lasting until next November, is "Murals in the Round: Painted Tipis of the Kiowa and Kiowa-Apache Indians." The only thing more appealing than painted Indian tepees, or tipis, is miniature painted tepees, and these twenty-five, made for the Smithsonian at the turn of the century, are thirty-inch scale models in deerskin, most of them mounted flat on the walls, but a few exhibited in the round. The other lively exhibit, "New Ways With Paper," uses that traditional art base as a medium this time. The artists have played with layers and folds, the paper having been dyed, embossed and imbedded as well as painted. The exhibit includes the experiments of Josef Albers, Louise Nevelson, Sam Gilliam, Claes Oldenburg, Robert Rauschenberg, as well as renowned paper makers.