The Rainbow Word series takes the 500 most common words in the English language (similar to Fry and Dolch words) and groups them into different levels, based on difficulty, for easier learning by students. The levels are red (easiest), orange, yellow, green, blue and purple (most difficult). Students experience success by mastering the easier words first, and working their way up through longer words with non-phonetic spellings. In addition, there are five different groups of 100 words. The first 100 are for beginning readers in kindergarten. The next level is appropriate to first grade readers. The third set of 100 words is mid/late first grade and the fourth set is for beginning second grade, etc. Of course, any student, including kindergarten students, could master all 500 words with this program.