She was always playing unkind practical jokes on other people.

It is true, she was an intimate and close friend of Miriam Nesbit, but they all were aware that Miriam was a law unto herself, and none of them had ever attempted to explain certain doings of hers in connection with Julia Crosby and her friends during the freshman year.
Grace's mind was busy with these thoughts when the door of the gymnasium opened noisily.

There was a whoop followed by cries and calls and in rushed the junior players, most of them dressed in gymnasium suits.
Julia Crosby, at their head, had come with so much force, that she now slid halfway across the room, landing right in the midst of the sophomores.
"I beg your pardon," said Grace, who had been almost knocked down by the encounter, "I suppose you did not notice us.

But you see, now, that we are in the midst of practising.

The gym.