A study investigated the effect that task instruction sheets had on the performance of vocational horticulture students when being taught a unit on poinsettia production. Using a post-test only control group design, researchers administered a 35-item multiple choice test on poinsettia production to 207 students in 12 randomly selected eleventh grade vocational horticulture classes. Of the 207 students participating in the study, 90 were in the control group and 117 were in the experimental group. Before being asked to complete the test, classes in the experimental group received a series of task instruction sheets on poinsettia production along with a monograph describing the nature and use of task instruction sheets. Classes in the control group received neither the task sheets nor the monograph. It was concluded that task instruction sheets are capable of causing significant increases in student achievement and that, as such, they should be given consideration as an important element of effective laboratory management. Based on these findings, recommendations were made calling for the integration of task instruction sheets into normal units of study included in vocational agricultural courses with extended laboratory periods and for the development of packages of such task instruction sheets in specialized vocational agricultural taxonomy areas. (MN)