If they are not able to say the word then pressing the "Again" button will have that word listed again after completing the entire list. From Wikipedia, the free encyclopedia: The Dolch Word List is a list of frequently used words compiled by Edward William Dolch, PhD.

The list was originally published in his book "Problems in Reading", The Garrard Press, 1948. Dolch compiled the list based on children's books of his era. The list contains 220 "service words" that have to be easily recognized in order to achieve reading fluency.

The compilation excludes nouns, which comprise a separate 95-word list. Many of the 220 Dolch words can't be "sounded out" and have to be learned by sight. Hence the alternative term "Sight Words". Although the list is divided into grades, for native English speakers, all the words in the Dolch should be mastered by the end of 1st grade.