Maridon Museum, 322 N. McKean St., will host a class on the game mahjong for beginners from 12:30 to 3:30 p.m. Friday as well as Sept. 5, 7, 12 and 14. Mahjong is a tile matching game. The class is free, but reservations are necessary. Call 724-282-0123. The Maridon is open 11 a.m. to 4 p.m. Wednesdays through Saturdays. Admission is $4 for adults, $3 for senior citizens and students, and free for children younger than 8. Tours are available with advance notice.

Saxonburg Area Artists Cooperative, 215 Main St., rear, Saxonburg, is open 1 to 9 p.m. Fridays and 10 a.m. to 8 p.m. Saturdays. Admission is free. Call 412-260-5779, 724-352-1795 or 412-849-4648. The gallery will feature art demonstrations during the Saxonburg Festival of the Arts Sept. 8 and 9.

Carnegie Museum of Art, 4400 Forbes Ave., presents “Natural History,” an exhibition that explores the ways contemporary artists respond to nature, through Oct. 14. Hours are 10 a.m. to 5 p.m. Tuesdays through Saturdays, with additional hours until 8 p.m. Thursdays, and noon to 5 p.m. Sundays. Admission is $17.95 for adults, $14.95 for senior citizens, $11.95 for students and children ages 3 to 18, and free for children younger than 3. Call 412-622-3131 or visit www.cmoa.org.Society for Contemporary Craft, 2100 Smallman St., hosts “Humor in Craft” through Oct. 27. This exhibition features works by 32 artists. Hours are 10 a.m. to 5 p.m. Mondays through Saturdays; closed holidays. Admission is free, but donations are accepted. Call 412-261-7003. A glass exhibit, celebrating the 50th anniversary of the development of studio art glass in America, is going on through Sept. 30 at the satellite gallery at BNY Mellon Center, 500 Grant St., in the lobby of the Steel Plaza T-Station.