Principals and administration need to know the basics: that learning in America is heavily dependent on good communication and that good communication is dependent on good acoustics. The reading list is not long: Classroom Design for Good Hearing, (PDF version), Classroom Acoustics I and II, A Quieter School: An Enriched Learning Environment, and the Classroom Acoustics Standard. But mostly, principals need to know that classrooms are either noisy or quiet by design! Classroom architecture and building materials make all the difference. The choices you make will determine if your classrooms are good learning environments.
Building a classroom without good acoustics is like building one without blackboards, white boards, or overhead projectors. Good textbooks, good curricula, and good teachers can't make up for poor classroom design.
Principals also want to know:
1. How much does it cost?
2. Who can help design a quiet school or quiet an existing one?
Other useful information:
How to test noise levels in an empty classroom?
How to test for excessive reverberation?