Sets and Systems, a series of fifteen- to thirty-minute mathematics training programs for elementary mathematics teachers, was tested in four locations in the northeast involving twelve pilot centers and 92,000 pupils. The programs were designed to familiarize elementary school teachers with some of the newer mathematics concepts taught in grades 1-8. The evaluation focused on three questions: (1) teachers' familiarity with these contemporary mathematics concepts and their attitudes toward issues concerning mathematics teaching; (2) changes in knowledge and/or attitude; and (3) whether or not these changes are reflected in teaching, as measured by student achievement and attitude toward mathematics. Preliminary data analyses focused on item difficulty when the tests were administered to teachers. Of 100 items from five achievement tests, 30 items had difficulty indices exceeding 14.25, while 29 had indices less than 11.75. Nine concepts were of considerable difficulty, fourteen caused more than average difficulty, and fifteen presented only minor difficulty.