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B. Nožica, M. Čarapina, O. Staničić

Polytechnic of Zagreb (CROATIA)
The idea behind CBM (Certainty Based Marking) feature in quizzes is to get more than just answers to M/C (multiple choice), true/false or short answer questions. After selecting an answer, the student has to evaluate his certainty level about correctness of a given answer, usually by selecting low (C=1), mid (C=2) or high (C=3) option. Depending of a grading schema built in CBM, the system calculates marks for a combination of given answer and level of certainty. The grading schema that is built in LAPT (London Agreed Protocol for Teaching) software and Moodle (from ver. 2.1) gives for certainty levels 1, 2, 3 matching marks (1, 2, 3) when an answer is correct, and marks 0, -2, -6 when an answer is wrong. Despite many benefits that CBM promise, it is not widely used. One of the reasons could be the “cruelty” of shown grading schema, especially if applied in shorter M/C quizzes - results on such tests could be devastating, even when more than 80% of given answers are correct. It seems that the given grading schema, although universal, gives best results when applied on quizzes with large number of true/false questions. One of the possible grading schema, that promise to be more optimized for M/C questions, is the one that gives for certainty levels 1, 2, 3 marks 1, 3, 4 when an answer is correct, and marks 0, -2, -5 when an answer is wrong. This schema is applied in CBM feature within Moodle that is experimentally in use for the courses of programing at Polytechnic of Zagreb.