Here is a game to reinforce the Circle of Fifths. You simple match the sunglasses to the correct key on the sun. You could simple use the sun part and have students write the key. As always, for a worksheet that will last and last you can laminate it or put it in a page protector.
This new version adds a back to the cards and sunglasses that only have one key on them. You could just focus on minor keys or major keys. The cards could also be used a lone for a matching game.