No self-respecting lefty college kid in the 1980s and ’90s was without a reproduction of something by Barbara Kruger. Perhaps it was her black-and-white image of a hand holding a message in bold, white-on-red type: “I shop therefore I am.” Or the iconic distillation of how the oppression of women has played out for centuries, printed over a woman’s face: “Your body is a battleground.” They circulated as postcards, magazine clippings and unauthorized photocopies, stuck to the refrigerator with magnets, tacked to your dorm-room corkboard or taped to the composition books in which you recorded lecture notes. Some people wore them on their bodies, emblazoned on T-shirts at anti-apartheid protests and ACT UP marches for AIDS awareness. “Thinking of You. I Mean Me. I Mean You.,” an extensive and engaging Kruger exhibition that opened at the Art Institute of Chicago last month, is her first major solo show in two decades. In the four decades since Kruger emerged as one of this country’s most uncompromising conceptual artists, the media landscape has changed almost beyond comprehension. But Kruger has kept up with it, turning to different modes of presentation and media, refining her messages, sharpening her wit. As new generations encounter her work for the first time, they will find it as bracingly smart as when their parents discovered it.