Enslow Publishers' new "The Constitution and the United States Government" series provides a compact, useful resource to address these needs. This five-title series offers age-appropriate, reliable background on the various governmental branches, the principal national security agencies, and the Constitution itself. Each book is 104 pages long, features well-chosen illustrations, and includes excellent citations for further reference.
All titles in "The Constitution and the United States Government" are available now from Enslow Publishers. Library-bound editions are available for $23.95; the price represents a 25% school/library discount from Enslow's list price for these items.