Check in weekly for listings of new exhibitions and activities of the yearlong Pittsburgh celebration of all things glass.

Tonight -- 6 p.m., lecture by Steve Sizelove, a Richmond, Ind., resident who received the 2005 Niche award in the category of goblets and was included in Lark Books' "500 Glass Objects," and president and director of Desert Glasshopper Studio & Glass Academy in Cave Creek, Ariz.; and Peggy Pettigrew-Stewart, a pioneer in working with float and optical glass and creator of "Plasma Fusion Glass," her signature medium. At the Pittsburgh Glass Center, Friendship (free; 412-365-2145 or www.pittsburgh glasscenter.org).

Saturday -- 10 a.m., weekly glassblowing demonstration and tour, Pittsburgh Glass Center ($10, $5 children; 412-365-2145).

Continuing exhibitions are listed in the Thursday Weekend Mag calendar.

-- Compiled by Mary Thomas