Explanation: A bell is used to alert us of many things such as a door bell, telephone bell, school bell, clothes dryer bell, etc. When we hear the bell, we know what the bell represents. To ring a bell became a way of saying that you remember something. Another explanation comes from Pavlov. He created an experiment where he rang a bell before he gave food to a dog. He did this repeatedly and the dog started to drool before he saw any food because the dog knew the food would come after the bell rang.