Card 30 of 82
The Mysterious Key
Every night before going to sleep, Lisa locks the door of her house and attaches the key to a string. Why?
Solution: Lisa was a sleepwalker. Some days before, she had left the house in the middle of the night without realizing. To prevent it happening again, each night she tied the key by a string to a bell. That way, if Lisa tried to leave the house, her husband would wake up and take her back to bed.