A preposition tells the position of an object. A preposition always comes at the beginning of a prepositional phrase. The last word of a prepositional phrase is the object of the preposition – and that is always a noun.
Here is a prepositional phrase – showing position: under the sofa
The preposition is under. The object of the preposition is sofa.
The word sofa is a noun.
Look at these examples of a prepositional phrase in a sentence:
Dad went up the stairs.
The book is on the table.
A plane flew over our house.
Notice that the last word of each prepositional phrase is a noun – stairs, table, house
Use a noun as the object of a preposition when writing a prepositional phrase.
It’s your turn. Find the prepositional phrase in this sentence. Then identify the object of the preposition. My cat hid behind the door. Did you pick out the word door as the object of the preposition? Good for you!