This study was concerned with the validation of the Oklahoma Curriculum and Instructional Materials Center's agricultural mechanics curriculum manual and the development of a model whereby future manuals can be validated. Five units in the manual were randomly selected from a list of units to be taught during the second semester of the 1977-78 school year: servicing small engines, overhauling small engines, electrical safety, fundamentals of electricity, and electrical wiring practices. Ten teachers were selected to teach the units, administer the unit test, and send the tests to the project staff. Results were compiled by determining the percentage of students at each school who obtained the correct answer on each item of the unit test. The school results were combined to obtain the total percentage of students who answered the items correctly. It was arbitrarily determined that 80% of the students should answer each item correctly to demonstrate acceptable achievement. Those items not passed by 80% of the students were reviewed to try to determine the reasons why. Based on student achievement, the manual provided a valid source of instructional materials for servicing small engines. It was concluded that one source could not be identified as the sole reason that learning does or does not take place. (Thirty-one data tables and discussion of analysis on the individual test questions are included.) (JH)