Here's why:
* Proper nouns are specific names of people, places, or things. They are always capitalized. Examples include:
* People: John, Mary, Queen Elizabeth
* Places: Paris, Australia, Mount Everest
* Things: iPhone, Chevrolet, Titanic
* Pencil erasers and sharpeners are general terms for types of objects. They don't refer to a specific, named item.
Examples:
* "I need a pencil eraser to fix my mistake." (General term)
* "My favorite eraser is the one with the pink unicorn." (General term)
Let me know if you have any other questions about proper nouns!