In assessing compensatory damages for legal remedies in tort, what is foreseeability?

Hypo 1: Bob just got a new shipment of fireworks from an illegal website (different tort involved there probably) and, in his excitement, decides to set off a small one in his living room. As he sets it off, his roommate Sam rounds the corner and gets hit right in the face with the firework, burning off his eyebrows. Result: Bob didn't mean to hurt anyone, but it was foreseeable that his irresponsible act could have hurt someone. He could have started a fire, launched it out the window and hit someone, any number of things. Since we know that Bob's action caused Sam's injury and Bob should have known (because it was foreseeable) that his actions could hurt someone. Thus, he should be liable for damages.

Hypo 2: Amy got a sick pair of nunchucks as a gift from Bob and she's always wanted to own a pair. She decides to practice with them and goes into her room with the door closed. As she's in there discovering her true shaolin potential, her roommate Jill opens her door to ask Amy a question and gets whacked in the face. Result: While Amy swinging her nunchucks was the proximate cause of Jill's fresh pair of black eyes, she couldn't have foreseen that injury. We know she took fair precautions––she went to her room to practice alone––so this case fails the foreseeability test and Amy shouldn't be held liable. That being said, on an exam, it would be wise to try to argue both sides of issues like these, as some may say that nunchucks are never appropriate inside of the house — mostly my Mom... my Mom would say that.