I also found out that:

"Hannah had the unhappy distinction of being the first of Harry's year to crack under the strain of O.W.L. study, requiring a Calming Draught from Madam Pomfrey after she broke down crying in Herbology, saying she was too stupid to take her exams (OP27). Accidentally multiplied a ferret into a flock of flamingos during the Transfiguration practical (OP31) but acquitted herself well in the confrontation with Malfoy on the Hogwarts Express (OP3. "