Note: RR = "Research-related," designating a link to a reference or to more information about relevant papers, reports, or studies.

See:

Kruidenier, J.R. (2002). Research-based principles for Adult Basic Education reading instruction. Washington, DC: National Institute for Literacy, pp. 41-42 and p. 50.
http://nifl.gov/publications/pdf/adult_ed_02.pdf (716k)