Read the excerpt of a story below. What causes Jen's homework to catch fire? Jen took the matchbox into her hands. She had never seen matches before, but she had an idea of how they worked. She took a match from the box and scratched it on the side. Nothing happened. She tried again, setting off a tiny spark. On her third try, a flame erupted. Startled, she threw the match onto her desk. Her homework quickly caught fire.