DIBELS Initial Sound Fluency (ISF)

The DIBELS Initial Sound Fluency (ISF) Measure is a standardized, individually administered measure of phonological awareness that assesses a child's ability to recognize and produce the initial sound in an orally presented word (Kaminski & Good, 19961998Laimon, 1994). The ISF measure is a revision of the measure formerly called Onset Recognition Fluency (OnRF). The examiner presents four pictures to the child, names each picture, and then asks the child to identify (i.e., point to or say) the picture that begins with the sound produced orally by the examiner. For example, the examiner says, "This is sink, cat, gloves, and hat. Which picture begins with /s/?" The student then points to, or says the name of, the correct picture. The student is also asked to produce the beginning sound for an orally presented word that matches one of the given pictures. The examiner calculates the amount of time taken to identify/produce the correct sounds and converts the score into the number of initial sounds correct in a minute. The ISF measure takes about 3 minutes to administer and score, and has over 20 alternate forms to monitor progress. The ISF measure takes about 2 minutes to administer and has 20 alternate forms for monitoring progress.

ISF administered is administered in Kindergarten. See the DIBELS administration timeline for complete information. For technical information about the ISF measure see our technical reports.

How does ISF link to the Big Ideas in Beginning Reading?

ISF is a measure that assesses phonemic awareness skills.

Phonemic Awareness (PA) is:

  1. the ability to hear and manipulate the sounds in spoken words and the understanding that spoken words and syllables are made up of sequences of speech sounds (Yopp, 1992).
  2. essential to learning to read in an alphabetic writing system, because letters represent sounds or phonemes. Without phonemic awareness, phonics makes little sense.
  3. fundamental to mapping speech to print. If a child cannot hear that "man" and "moon" begin with the same sound or cannot blend the sounds /rrrrrruuuuuunnnnn/ into the word "run", he or she may have great difficulty connecting sounds with their written symbols or blending sounds to make a word.
  4. a strong predictor of children who experience early reading success.

To learn more about phonemes, phonemic awareness, and how to design and implement effective phonemic awareness instruction, visit the Big Ideas in Beginning Reading website.