Cover the basics. Teach simple prepositions such as "on," "in," and "under" first, especially, if you are teaching students whose native language is not English. Get a box and ball. Hold the ball in various positions around the box and elicit responses. Encourage your students to shout out the correct preposition.
Make up a song with actions. Pick a well-known children's song like "Frere Jacques," and replace the words with prepositions. Use your hands to indicate the position of the ball in relation to the box at the same time. This will provide a mnemonic resource that sticks in your children's minds.
Make up a game. For example, pass out assorted geometric shapes to all the students. Yell out commands that involve prepositions, such as, "Put the circle over the square." The winning student is the one who completes the actions the fastest.
Review what you've taught. Get the students to make sentences using prepositions, and correct the students if they make mistakes. Similarly, give them some sample sentences and have them underline the prepositions in each.
Move on to more advanced prepositions. If your class is ready, teach them more difficult words such as "despite," "excluding" or "concerning." These prepositions will be harder to demonstrate and should be taught through examples.