Introduction : Use of worked examples is one of the methods to decrease cognitive load and facilitate learning. There are different methods to provide worked examples. The aim of this study was to compare the effect of two teaching methods of complete and incomplete worked examples on students’ cognitive load in instruction of medical terminology.

  Methods : In a quasi-experimental study in 2013 in Semnan, 77 students who had chosen the course of medical terminology for the first time, were selected and randomly allocated in two groups, one trained through complete examples and the other through incomplete (completion) examples. Students’ cognitive loads were measured using a subjective cognitive load scale during study and examination. Findings were analyzed using parametric statistical tests.

  Results: The findings of this study showed that mean of cognitive load of students in complete example group was 16.83±6.58 during study and 26.59±5.98 during examination out of a total of 36 points. Students’ mean score of cognitive load in incomplete example group was 17.33±5.79 during study and 26.55±5.15 during examination. Statistical analysis did not show any significant difference between cognitive loads of two groups during study and examinations. However, during the study, the cognitive load of students of emergency medicine in associate degree (21.21±5.24), emergency medicine in bachelor degree (15.63±5.64), and operating room in bachelor degree (13.9±5.05) was significantly higher compared to students of other disciplines (P=0.001). The findings showed that there was a relationship between cognitive load during study and during examination (P=0.01).

  Conclusion : Although cognitive load in complete example group and incomplete example group did not show a significant difference in this study, worked example could be used as a teaching method. Further studies are needed with emphasis on the structure of examples, involving students in working examples and use of these examples.