A common noun can name a thing. Common nouns are always written with lower-case letters.
Here are some examples of common nouns that name things:
box
car
truck
book
toy
fence
chair
desk
shoe
pencil
lamp
Any word that names a common object is a common noun. A common noun is never capitalized.
▶It’s your turn. Find two common nouns that name a thing in this sentence. Sally put her shoe on the chair. Did you find the two things that are common nouns? Good for you!