This training manual is intended to enable educators to utilize the SAGE Tri-Fold Model as a means for developing a process-oriented differentiated curriculum for elementary grade gifted students using either the separate classroom, the resource room, or the consultant teacher model. The program, a nationally validated National Diffusion Network Program, is based on those theories found to be most workable in the areas of identification, program planning, curriculum development, and evaluation. The tri-fold model refers to the three key elements of the curriculum: (1) thinking skills development, covering critical thinking, logical reasoning, creative thinking, creative problem-solving, and research skills; (2) mini-study units for the inclusion of enrichment materials which are broad-based, interdisciplinary, and incorporate thinking skills into content areas; and (3) independent study involving individual or group projects and allowing in-depth study of special interests as well as linking students to mentors. An extensive introduction describes the curriculum, presents its theoretical basis, offers guidelines for student selection and parent/teacher training, and discusses in depth each of the three curriculum components. The major portion of this document consists of about 50 complete mini-study units in the areas of science, literature, social studies, art, and miscellaneous. The units contain objectives, research questions, and activities. Appendices provide nomination forms, giftedness identification forms, information on thinking skills, and curriculum differentiation forms. (Contains a 27-item bibliography.) (DB)