Mathematics books for children & young adults and for teachers are in the CMC area (lower level). Most math realia and manipulatives are shelved on the west wall of the lower level near the CMC book shelves.
Primary Source Nexus
Primary Source Nexus is a website geared toward K-12 teachers to help them incorporate primary sources into their lessons. The primary sources are a part of the Library of Congress digital collection. The site also has lesson ideas, themed link sets, and more. Definitely a must look!