These little gems are called Color Rings in my class. They are leveled flashcards for advanced kindergarten. My class started on an almond color ring that has all of the letters and color words. In order to pass the almond ring and move on to the next, the student must name all letters and the corresponding sounds, as well as all of the color words. They must be able to get through the whole ring with no mistakes in order to move on to the next. The rest of the rings cover a total of 240 sight words. They keep the color ring at home and practice with their parents until he or she is confident that they will make no mistakes. I will then test them on the particular ring.
This is not a mandatory assignment, but It really gives them an advantage for first grade. Plus, many Kinders jump at the opportunity to learn more sight words in a more structured way.
The color rings progress in this order:
I'll post a picture of all of the color rings together later.