Collaboraction's fourth annual Sketchbook opens tonight at the Chopin Theatre. Sketchbook comprises 16 new short plays, performed in a different grouping of 8-10 each night. The theatre will also feature the work of 14 visual artists and 10 sonic artists as part of the sketchbook environment. The show runs 13 consecutive nights; the closing night finale, April 4, will show all 16 plays beginning at 3pm.