Prepositions: one of the hardest grammatical concepts for ELs. One of the things we practice is telling the difference between literal and figurative use of prepositions. After discussing prepositions as relationship/location words (see here), we discuss other phrases that use prepositions to talk about the locations/times of other things. The students then illustrate an example of both uses of a preposition. Here are some of the results:
thoughts and songs 
Wow, two posts to your blog in one day! My Blogger Dashboard can barely handle all the updates.
To my knowledge, I probably haven’t thought about literal vs. figurative use of prepositions since either 8th grade or Intro to Elementary Greek. But I imagine it is a very important concept for teaching the language to folks for the first time.
Nice charts too!