You can see in the example that there is a high degree of similarity between all parts of the submission for the two students. In drawing UML there are very many possibilities. Placement and naming of items in the diagrams are too similar to be coincidental. The repetition of serious errors such as the use of a rectangle instead of an elipse to depict a use case in the use case diagram, was only found in these two submissions (and not in the other 145 submissions).

In the textual answers in which the students had to identify errors in a number of UML diagrams they were given, we can again see a lot of similarity but also an attempt to change the words and hide the plagiarism. A telltale sign that plagiarism has occurred is that only a small fraction of the actual errors were found, the ordering is similar and again student errors were repeated in both. The written section would probably not have been detected, except that once copying was found in the drawing section, the written section was checked as well.

UMLPlagiarism.pdf