If a teacher gives a test to one set of students in the first session. Then the same/very similar test to the second set of students an hour later, may a student from the second session receive information about the test from the students who already took the test?
I’m not sure if this makes any difference but the Dean of the school made an announcement in the beginning of the year that if you ever have a question if something is cheating, then you should ask the teacher. Does this change anything?
This would be considered cheating on the test.
Cheating on a test is a good case of geneivas daas, and it can also be considered a monetary prohibition if the grades are used in the future for monetary benefits, for getting into institutions, and so on.
Note that the Tosefta (Bava Kama 7:3), as cited by the Ritva and other authorities, states that of several types of thieves (three, or seven, depending on the textual version of the Tosafta), geneivas daas is the more severe. It is therefore worthy of being stringent in this regard. See also Rambam, Hilchos De’os 2:6.
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