This booklet is the final report on a project designed to determine the extent to which students in grades 2, 3, and 4 who were having particular difficulty in learning number concepts were not yet conserving number. A test of number conservation was given to all children assigned to the remedial group; 10 of the 23 were found to be nonconservers. The nonconservers were given special instruction using manipulative materials; five of these students were classified as conservers on the posttest. A similar instructional treatment for grades 5 and 6 was developed, used, and found to be successful. Appendices to the report include a copy of the conservation test, a list of materials purchased, and copies of lesson plans and locally made activity sheets. (SD)