Organization: Institute of Education Sciences, What Works Clearinghouse
Spelling Mastery is designed to explicitly teach spelling skills to students in grades 1 through 6. Spelling Mastery can be implemented with individuals or whole classes. The program is designed for all academic levels: advanced, average, and academically challenged. It can also be used in multiage classrooms, with English language learners, and with students with learning disabilities. The What Works Clearinghouse review of Spelling Mastery for the Students With Learning Disabilities topic area includes student outcomes in nine domains: alphabetics, reading fluency, reading comprehension, general reading achievement, mathematics, writing, science, social studies, and progress in school. The two studies of Spelling Mastery that meet What Works Clearinghouse evidence standards reported findings in one of the nine domains: writing.
http://ies.ed.gov/ncee/wwc/Docs/InterventionReports/wwc_spelling_mastery_100716.pdf