You'll find free downloadable resources, many in PDF format, in various parts of TEFL.net, for example Lesson Plans and Worksheets. Below are additional free ebooks and downloads.
English Prepositions List
This downloadable ebook, English Prepositions List, shows English prepositions and gives example sentences for each one. Prepositions can be divided into one-word prepositions (after, in, under) and complex prepositions (apart from, because of, in spite of). This ebook lists almost all the one-word prepositions and most of the complex prepositions.