He has to purposely fail tests to lower Godfrey’s expectations, and he’d have to study in order to definitely find out the wrong answers, even though there would be a a/b (a + 1 = b) chance of getting the wrong answer on multiple choice problems, and on true/false tests he’d have a 1/2 chance on that, and on essay tests, he’d have a larger chance to fail, and so, that’s the preparation for the gag.
Got a point there.