You're talking about "OBT Exposed!" It's not a performance, but a very popular opportunity to observe a few days in the life of a professional dancer. The audience watches OBT company members go through their normal schedule of full class and day-long rehearsals. The schedule is something like 10:00 to 4:00, if I remember correctly.
You're expected to be fairly quiet--after all, it's their "office"--but it's certainly a more relaxed atmosphere than a performance would be. You're welcome to come and go, eat your lunch, and (at certain times) even ask questions.
"OBT Exposed!" is held under a large tent in Portland's South park blocks (between Eighth and Ninth, near Salmon) around the end of summer. The OBT office will have the exact dates. Their number is 503-227-0977.
