SAM’s efforts to add short-term, seasonal installations to the Olympic Sculpture Park haven’t been enormously successful. Temporary works mean cheaper materials that can be easily carted in and out of the site. The big, permanent pieces dominate the grounds; it’s almost impossible to add anything new that would upstage the old. Yet Heather Hart’s verbosely titled The Western Oracle: We Will Tear the Roof Off the Mother has proven to be wildly popular since being built onsite in May. I’m not even sure that the roof, which suggests a house sunk into the west-facing slope, is even art. Most people view it as an object to be climbed, where they can pose for photos or nap on the shallow-angled roof. There’s a whimsical incongruity to the thing that for me, at least, recalls the house crashing down on the Wicked Witch in The Wizard of Oz. Hart’s half-domicile looks to have been buried there by some cosmic force. An ex-local who trained at Cornish and now works in Brooklyn, she built the thing with the aid of her father. Most visitors tread on top of Western Oracle (SAM has posted various safety warnings and disclaimers—wear appropriate shoes! and no pregnant ladies!), but they can also stoop down and enter inside. Hart writes, “A visitor is invited to approach a window that looks out onto the Puget Sound and sit under a chimney that looks into the sky. The window is framed in a wall that acts as a drum, referencing local histories and providing means for a sound exchange as prayer, ritual, expression, and fun.” Fun. There’s a word you don’t often hear in art criticism, and that’s what makes Western Oracle such a success. The piece is a refreshing alternative to the usual “Do Not Touch!” mantra of museums and galleries. Maybe next summer SAM should commission a proper jungle gym. Olympic Sculpture Park, 2901 Western Ave., 654-3100, seattleartmuseum.org. Free. Open daily. Ends Oct. 13.