Check these sites for curricula, lesson plans, statistical data, and other resources.
Arts Edge (Kennedy Center program) - arts integrated lesson plans cataloged by subject and grade level, tailored to national standards.
ArtsWork - Arizona State University - Combines ASU artists and scholars with community leaders in research and program focused on children and the arts - lesson plans and more.
Carnegie Hall Digital Library - Games and listening guides.
Classical Net - biographies, timelines, instruments, musical eras.
Conn-Selmer Educational Resource Center - brass/woodwind/string method books, fingering charts, rehearsal/teaching guides.
Idea Bank - lesson plans.
Keeping Score - by Michael Tilson Thomas and the San Francisco Symphony. "provides innovative ... classical music content on PBS ..., the radio, the web, and through an education program, a national model for classroom arts integration for K-12 teachers.
Lesson Planet - lesson plans graded by working teachers.
MHMusic: Spotlight on Music - Orff orchestration lesson plans
Music Education Online - website of the Children's Music Workshop.
Music Graphics Galore - collection of music icons, clipart, graphics, and backgrounds.
Musicians with Apps - free or inexpensive apps.
OrffSite - lesson plans, podcasts, PowerPoints
Support Music (by NAMM and NAFME) - "...tools and resources to advance community support for music education."
TheTeachersCornet.net - activities and lesson plans.
teAch-nology - K-12 lesson plans.