COUNTYHarmony Museum, 218 Mercer St., offers museum tours from 1 to 4 p.m. daily except when the museum is closed Mondays. Admission is $7 for adults, $6 for senior citizens, and $3 for youths ages 6 to 17. Call 724-452-7341.

PITTSBURGHCarnegie Science Center North Side, presents Engineer the Future on Friday and Saturday with hands-on activities and science demonstrations designed to inspire young people to explore engineering. General admission is $18.95 for adults and $11.95 for children ages 3 to 12. Visit CarnegieScienceCenter.org.ToonSeum, Pittsburgh's Museum of Cartoon Art, 945 Liberty Ave., hosts “Alt-Weekly Comics,” a historical retrospective dedicated to the comics of the alternative weekly newspaper world, and “Fear of a Black Marker: Cartoons by Keith Knight, Gentleman Cartoonist,” both through April 10. Admission is $8 for those 13 and older and $4 for children ages 6 to 12. Visit toonseum.org.National Aviary, 700 Arch St., presents a baby Linnaeus' two-toed sloth that recently joined the flock. Admission is $14 for adults and $13 for senior citizens and children ages 2 to 12. Hours are 10 a.m. to 5 p.m. daily. Visit www.aviary.org.Children's Museum, Allegheny Square, presents the play exhibit/art installation TapeScape 2.0, showing unusual uses for packing tape, through May 22. Hours are 10 a.m. to 5 p.m. daily. Admission is $14 for adults and $13 for children ages 2 to 18 and senior citizens. Visit www.pittsburghkids.org.