The top form took arithmetic with Miss Fanny. It was a subject which Opal disliked, but for the last two or three lessons she had worked all her problems correctly. Miss Fanny, who ought to have known better, left her Key to the arithmetic on the mantelpiece of the classroom, and one morning Mavis, coming in early, caught Opal in the very act of copying the answers to the next set of questions. "Well!" she exploded. "Of all mean sneaks you're the biggest I've ever met. No wonder you get all your sums right if you write down the answers beforehand. How _can_ you?" Opal tried to laugh the matter off. "Why don't you do it yourself, my dear?" she answered. "If Miss Fanny _will_ leave her book about, of course we look at it. That's human nature!" "It's not my way," said Mavis gravely. "And if Miss Fanny trusts us so much that she leaves her Key here, we ought to be worthy of her trust. It's shameful to deceive her." "Oh, Jonathan! Go and tell her, then." "You know I never tell tales." That day, however, Opal was unexpectedly overtaken by Nemesis. Miss Fanny was suffering from a severe headache, and Miss Pollard came to take the arithmetic class in her stead. The girls told her the number of the exercise they had reached, and she wrote the questions upon the blackboard. For some reason of her own she reversed their order. When she called for the answers, Opal, with great assurance, read hers out, and, of course, as she had copied from the book, No. 6 came instead of No. 1, and vice versa. Miss Pollard stared at her in much amazement, and told her to come and work them upon the blackboard, a process of which she made a conspicuous bungle. Miss Pollard made no special remark, but possibly her suspicions may have been aroused, for she carried away the Key, and it was never again left in the classroom. Whether her affection for Opal prevented her from making a closer inquiry, or whether the affair was merely a coincidence, and she still preserved her faith in the integrity of her pet pupil, it was impossible to tell. "All the same I call it the limit for her to shut her eyes to things in the way she does," commented Mavis to Merle. "Both Miss Pollard and Miss Fanny are dears, but a teacher ought to know something of what goes on in a school, and not leave it just to luck. What are we to do? We can't go sneaking and telling, and yet I feel we ought to make a stand. It doesn't seem right to let Opal behave like this and do nothing. She hasn't the slightest idea of honour." "That's what most of them need here," snorted straightforward Merle. "I know. But what can you expect with such a slacker as head girl? If only Mother were here I'd ask her, but I'm so stupid at explaining properly in a letter it's no use to write." "Not a bit. She wouldn't really understand. Seems to me there's nothing for it but just to worry on as best we can. They're a queer set, but we can't help it." CHAPTER X Among the Boarders