Plate blocks or control number blocks are designations given to a block of stamps, usually four, with a plate or control number present on the selvage. Such a block is usually located in one or all four corners of a pane. Federal stamps prior to 1959 plus the 1964 issue are collected in blocks of six and must have the selvage on two sides. The Federal Junior Duck Stamp Program is a non-profit program sponsored by the Federal Government and designed to promote interest in conservation and wetlands preservation among students in grades K-12. The program includes a conservation and education curriculum that helps students of all ages. It focuses on wildlife conservation and management, wildlife art and philately. All proceeds from sales support conservation education.