This instructor's guide is intended for use in teaching the agricultural mechanics unit of a plant science core curriculum. Covered in the individual units of the guide are the following topics: arc welding (following safety procedures, controlling distortion, selecting and caring for electrodes, identifying the material to be welded, and welding in horizontal and vertical positions); oxy-acetylene welding (following safety practices, fusion welding, brazing metal, and heating metal); power tools; painting; tool sharpening and reconditioning (reconditioning wood chisels, plane irons, center punches, and chain saws); cold metal work; and material selection, plan reading, and plan interpretation. The introductory section of the guide contains a list of behavioral objectives, suggested motivational techniques and interest approaches, a list of references and materials, suggestions for evaluating student performance, a work schedule for agricultural mechanics in plant science, and a time allotment for agricultural mechanics skills in animal science and plant science. Included in the individual lessons are objectives, study questions, a list of references, a detailed teaching outline, an evaluation instrument, and answers to the evaluation instrument. (MN)