Is this store bought or do you make your own? If I understand correctly the rainbow word wall is for placig the words each child can read. Is this right? Then do you use this instead of or in addition to a word wall (the abcs going across the wall with words under each letter)? Do you put up the rainbow board at the beginning of the year? How often do you add to it? What words do you add, sight words only, color words, number words...?