She led the way into the cheerful schoolroom, where big girls and little girls were sitting about, amusing themselves in the quiet of a long Sunday afternoon.  Several of the younger children ran to her as she came in, and stood holding fast to the folds of her black habit, staring up at the strangers, while she explained the kind of instruction given, the system, and the order reigning in each department.  Finally, she persuaded a little girl, only six years old, to take her dusky face out of the long flowing veil of the nun, and show how quickly she could read a sentence that Sister Winifred wrote on the blackboard.  Then others were called on, and gave examples of their accomplishments in easy arithmetic and spelling.  The children must have been very much bored with themselves that stormy Sunday, for they entered into the examination with a quite unnatural zest.  Two of the elder girls recited, and some specimens of penmanship and composition were shown.  The delicate complexion of the little nun flushed to a pretty wild-rose pink as these pupils of hers won the Colonel's old fashioned compliments. 
What day did the nun enter the schoolroom with the strangers?
Monday