How about taking photos of things on and under and printing them there and then? The kids could choose from a selection what they would place where; they or you if necessary take the photo; put the same object in the other positional relationship to the same thing and you have the cards for a barrier game - even if there isn't time to play it then. (Or you could have some ready that you made earlier...) If they can read, prepare possible printed sentences for the photos you've already made to be matched to them (use symbols for key words if possible e.g. pencil /on /plate and no symbols for the other words). Suggestions - as I have been this way before: on/under plastic zipped folder (you have to be able to see what is under); on/under a translucent upsidedown plastic box; on/under a plastic plate; on/under a book. Suitable objects are things that will not break, roll away, be too big for the 'cover' to fit on but may poke out a little so you can see them e.g. a pencil, a feather, a letter in an envelope, a bar of chocolate. Hope that helps. Good luck.