Moving on from Craig's postings, lol....
I've just found a nice little video from Prof Pillow on YouTube about how to make a picture reveal game in PowerPoint, so if you have that ichott, maybe that's something you could look into.
Here's one I quickly cobbled together. Click.
Click on each square in the grid to reveal it. Hope it works. : )
pdb1: I was noticing that the items don't standout as typically American.