Houghton MifflinÂ® (2003) support for 2nd grade story Thunder Cakes by Patricia Polacco. There are 4 sheets which include a fluency story, fluency words, and fluency story for homework. The fluency words are related to the word pattern for this story (ed,ing) & (gh,kn,b). The fluency story contains the vocabulary words of the week. These worksheets correlate to the story and help to build student's fluency.