Hi, Bill, You asked: 1) why would you suggest prepositions or conjunctions, rather than interjections? >> Because prepositions are an integrated part of speech, part of the grammatical structure of a sentence, whereas interjections are extraneous. 2) I don't believe that, for the 4 panel cards, every "possible" combination is included. As a matter of fact, I'm fairly certain that they aren't. It was one of the reasons I needed to create the chart, because there wasn't a specific "formula", as far as I could tell, for deciding which card combinations were included. Maybe when the Looneys get back from GenCon, if Andy sees all this, he can explain how the four panel combinations were derived. :-) >> If you lay them out in groups, you'll find that every card has four different images, in 5 pairs, where each pair omits a different one of the 5 images of the set; and each image occurs the same number of times, but with 4 on the right and 4 on the left. So the cards do constitute a set of all different combinations, though not in every possible different relative position. Each individual image can be seen as occurring the same number of times in all possible different positions on the 4 corners. Evidently an intriguing neighboring protocol was used: where they occur on the same card, stars and fish are always together; flames and flowers are always together; ditto rainbow and flame. With everything in the deck being in groups of 5 or 10 or 15, this arrangement of the 4-panel set was the most effective way to have all different combinations on just 10 cards. Quite a brilliant solution, wouldn't you say? If I've missed part of the formula, I'd love for Andy to explain it. You've probably noticed that all the 2-panel cards are a distinct pair, and all possible pairs occur once, both in the horizontal and in the vertical divides. In fact, such pairings always produce a triangular number, as in standard dominoes, hence 10 cards: 1/2, 1/3, 1/4, 1/5, 2/3, 2/4, 2/5, 3/4, 3/5, 4/5. Isn't this just the greatest fun? You can implicitly teach group theory, systems thinking, combinatorics, and organizing by matching elements. -- Kate