Instruction on Prepositions:
http://www.chompchomp.com/terms/preposition.htm
Practice: Choose the correct preposition AND label it as being used as a preposition or a conjunction.
http://a4esl.org/q/f/z/zz98bck.htm
http://www.wiziq.com/online-tests/4121-english-test-on-prepositions-for-toefl-ibt
And choose the mixed prepositions practice here:
http://www.englishpage.com/prepositions/prepositions.html
Assignment: A personal study.... As you go through the practice questions, record any sentence that you miss. Your goal is to find any error that you make repeatedly and learn why you are missing that specific error. Turn in these sentences (with the preposition underlined) and a paragraph of analysis to Mrs. West explaining your findings.