Answer:
Understatement version - "it's not that bad!"
Hannah rode her bike to school. She stowed it in the rack. She casually walked to homeroom. No way was she going to violate the hallway policy. When she got there she found that she was just a little bit late; the lunch bell rang.
Hyperbole version - exaggeration
Hannah peddled her bike as fast as she could to school, leaving trails of fire behind her. She stowed it in the rack. She was extremely late, so she ran to homeroom, a clear violation of hallway policy -- she could get expelled! When she got there she found that she was so much later than she had thought; the lunch bell rang. It was practically the end of the day!
hope this helps