Effects of Plagiarism in Introductory Programming Courses on the Learning Outcomes

[EN] We compare two introductory programming courses and the accompanying programming assignments with respect to the learning outcomes and the relation to plagiarism. While in the first course the solutions from the students of their programming assignments are checked directly with a plagiarism detection system to prevent students from plagiarizing, plagiarism is not tracked in the second course. Running a post check against plagiarism after the course reveals a significant higher plagiarism rate with several exact copies. As the number of students handing in copies from fellow students increases, the failure rate in the final examination also rises. Analyzing the data does not only reveal a correlation between plagiarizing and inferior examination results, but also shows, that students confronted with a plagiarism detection system have better skills in fundamental coding concepts. We suppose this might be a result of the fact, that the implementation of a plagiarism detection system does not deter so many students from plagiarizing, but students are strongly motivated to run more modifications on their plagiarisms in order not to be caught.