You need to see the tests. Why have you been unable to do so?
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We're encountering this. In our case, it's a result of math being moved on line, and the results end up in the netherworlds of the computer. The OP commented on multiple choice math tests, which is also consistent with our experiences.
In our case, we've emphasized with the school that the post-mortem is a vital component of the learning process and in test taking. Because the math teacher is less-than-optimally engaged with the instruction process, we've involved the councilor, DD's IS, and now the principal. Hopefully the OP can gain traction wtih just the councilor.
