This source is from the U.S. Department of Education, Institute of Education Sciences, What Works Clearinghouse (http://ies.ed.gov/ncee/wwc/)
Typically, the teacher selects a passage of about 50 to 200 words in length. If the student misreads a word or hesitates for longer than 5 seconds, the teacher reads the word aloud, and the student repeats the word correctly. If the student requests help with a word, the teacher reads the word aloud or provides the definition. The student rereads the passage until he or she achieves a satisfactory fluency level.