Pick up two of the face-down tin cans, shake each one. If the sounds are identical, you have a matching pair, keep it, and search for the next pair. The 12 pairs of tin cans have transparent covers, each pair contains different seeds of different size, weight (and color, though the latter does not play a big role here – one could use it also as a standard memory game for hearing-impaired people, of course). Some similar sized seeds produce VERY similar sounds, so the game is not at all easy. The game box also contains a booklet explaining the different seeds in detail (it unfortunately does not explain the game rules, but then any one familiar with Memory games will not need any explanation). "Horch" is kind of an old-fashioned German word for "Listen!".