what are examples of proper nouns?
 Tina offered Antonio one of her mother's homemade oatmeal cookies but only an Oreo would satisfy his sweet tooth. Cookies = common noun; Oreo = proper noun. 
Charlie had wanted an easy teacher for his composition class, but he got Mrs. Hacket, whose short temper and unreasonable demands made the semester a torture. Teacher = common noun; Mrs. Hacket = proper noun. 