In particular, the teacher could tell the student to take on various tasks or do experiments which might lead to a breakthrough, or possibly work to lower the student's level of background anxiety-- the latter is plausible to me because there might be a reason the student has no trust in his or her own perceptions and thoughts, and that reason might be locked in place by fear. Of course, I'm just guessing about a hypothetical student-- the teacher (if competent) should be able to form hypotheses about why the student is so stuck and what might help.