Prepositions are the parts of speech that describe the relationship between words in a sentence. Depending on the reference source you use, there are between 85 and 150 different prepositions. "A preposition usually indicates the temporal, spatial or logical relationship of its object to the rest of the sentence." For example, in the sentence "The radio is on the nightstand," the preposition here is "on," as it specifies the spatial relationship of the radio to its object, "the table." Learning prepositions involves understanding their grammatical function and then memorizing the most common ones.

Learn the most common prepositions in the English language. You can find a list of prepositions by performing an Internet search or by checking out a grammar book from your local library. Some dictionaries also have lists of prepositions as well.

Use flash cards to practice identifying the preposition in sentences. You can either purchase a set of preposition flash cards, or you can have a friend or a teacher simply write random sentences on the fronts of the cards, and then write the preposition of the sentence on the back.

Memorize the most commonly used multiple word prepositions. These include, but are not limited to, "as far as," "in to," "instead of," "on account of," "prior to" and "except for." You can also use flash cards to help yourself remember these as well.

Go online and find quizzes. A number of websites offer grammar quizzes covering all the different parts of speech. Whether matching, multiple choice or fill-in-the-blank, quizzes can often be a valuable tool for expanding your understanding of English grammar.