Developed for use in auto mechanics, Heavy Equipment Repair and Operation (HERO), and small engines programs, these study guides and supplemental worksheets cover operating principles, lubrication, cooling system, ignition circuit and electrical system, and fuel system. The worksheets and guide questions are phrased to emphasize key points designated by the program instructor and to aid in evaluating the technical information presented within the curriculum area. Although some worksheets specifically state that they were written for a particular specialized occupational program, they may be modified or adapted for use in other mechanical clusters. Specific contents include reading modules (vocabulary, informational material, questions, and answer keys) on operating principles, lubrication, fuel systems, carburetors, and carburetor circuits; worksheets of various types, including short answer, true-false, matching, multiple choice, identification, and cloze exercises. A separate section contains exercises in micrometer reading, mathematics and vocabulary. Study guides are also provided for use with the "Small Gas Engines" textbook. The final section contains cloze exercises. All answer keys are included. (YLB)