Two Old Mill High English teachers rolled a makeshift partition into the audience, separating themselves as they pretended to teach.

As Sean Swanson started to lecture, a louder, fuller-voiced Meghan Humbert followed suit. Both of their talks melded into gibberish as they as they tried to talk over each other.

"This isn't a far-fetched example of what it's like to teach at Old Mill," Mr. Swanson said.

The pair's plea to wall in their noisy, open-space classrooms was one of a handful voiced by teachers, parents and students on Tuesday night, the second of two hearings on interim Superintendent Nancy M. Mann's capital and...