Zach noticed and frowned.  He got up and walked up to the front of the class, standing in front of the girl who currently held Kat's sketchbook and holding out his hand.  "If you would?" he asked, trying to sound polite, though he wanted to give her a piece of his mind.  He hated bullies, but knew that yelling at them would just give them what they wanted, so he remained calm, though he stared her down as well.