A self instructional unit (SIU) on nursing care plans was tested to demonstrate its effectiveness on the cognitive performance of three different student achievement groups. Two other text formats: Question Text Type (QTT) and Information Text Type (ITT) were utilized to demonstrate their effect on the cognitive performance of the three achievement groups. The expectation was that the SIU would successfully improve the subjects' knowledge on nursing care plans, and that the post test scores would be related to the text types used during the study. The subjects were 48 B.Sc. (Nursing) degree students in the first year of a post-basic nursing degree programme who were divided into high, middle and low achievement groups, according to the results of a pretest on the theory related to nursing care plans. The results showed that the SIU significantly improved the basic knowledge of subjects on nursing care plans. Furthermore, the SIU and the QTT appeared to be superior to the ITT formats. On the whole there appears to be a relationship between text type and cognitive performance whilst students try to accumulate or review information.