Slightly discouraged he hadn't reacted to her tone, yet at the same time relieved since she really hadn't meant to sound quite that rude, Katara didn't say anything. She simply raised the crossbow and took aim. She was hoping, since she could hit just about any target - moving or not - with even the smallest drop of water, that she might be able to do well enough with the crossbow that they could move on to the next lesson.
Of course, she soon realized that wasn't the case. After all, with water, she could manipulate it while it was in motion and therefore counter any move made by her opponent. With the crossbow, once she pulled the trigger, that was it. Her part in it was done.
So rather than rush things, she took her time and truly tried to line up the shot as best she could considering she had no clue how. Once she thought she might be able to hit the target she exhaled slowly and squeezed the trigger.
And was promptly smacked in the fact by the crossbow as it kicked backward and upward.
With a yelp she dropped the weapon to the ground and brought her hands to her nose. She didn't even pay attention to the path of the arrow (which only grazed the target and ended up clattering ineffectively off the far wall) as she was too busy pinching her nose to stave off any possible blood flow while simultaneously glaring at Zuko with tears of pain in her eyes.
"You did dat on burbose!" she accused him, the words coming out odd-sounding and slightly muffled. There was no mistaking the anger in her tone, however, as well as the red spots of embarrassment staining her cheeks.