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Spelling Mastery 

Spelling Mastery is a program made by Direct Instruction. The program uses explicit instruction, scaffolding, and continuous feedback. While primarily teaching spelling through morphology and phonology, the program also includes direct vocabulary instruction for commonly used, irregularly spelled words. It uses phonology to teach phonemes that are consistently used; while also teaching root words, suffixes, and prefixes. 


Previous Reviews:

What Works Clearing Houe evaluated 2 studies on the Spelling Mastery program. These studies included a total sample size of 70 and examined instruction for grades 2-4. WWC evaluated the rigor of these studies as promising and found a mean effect size of .85. They I searched for studies on the program on the company website, Google, Education Source, and Scholar's Portal. That being said, I was able to find two peer-reviewed studies, with control groups, that I could draw effect sizes from. For both articles, the authors had calculated their own effect sizes. 

Both studies were by Darch, Et al. The first was conducted in 1990, was an RCT, and used 28 grade 4 students as a sample. The study included 12.5 hours of instruction. The second study was done in 2006. This study was conducted on 42 grade 2-4 students and included 8 hours of instruction. Both studies were specifically on students with learning disabilities. The 1996 study yielded a mean effect size of 1.26 The 2006 study yielded a mean effect size of .38. Which resulted in a mean effect size of .82. 


There are only two studies powering this result and the results between the two studies were dramatically different. The first study showed very high yield results, whereas the second showed moderate to low results. That being said the mean result is far above average, especially for an intervention program. I have put an infographic below for comparison. That being said, I do not think it is entirely fair to compare the Spelling Mastery program to most other language programs, as it is only a spelling program and not a reading program.

It is unsurprising that the program results were as high as they were, when you consider its methodology. Phonology is a more efficient focus for teaching the English language, as it is more broadly applicable. However, studies have shown morphology is better for spelling, likely because the English language is primarily a morphological language. Knowing phonemes can help you sound out a word, but they cannot tell you which letters to use when spelling an unfamiliar word, only morphological knowledge can do that. That being said, there are also many short, frequently used irregular words that are probably best learned through rote memorization. The Spelling Mastery program appears to reflect all of these truths. 

Final Grade: B+

1 high quality study found a mean effect size of above .70. A non-peer reviewed meta-analysis of the program yielded an effect size of .82. 


Qualitative Grade: NA

I did not include a qualitative grade for this program, because it is not a full literacy program, but rather just a spelling program. 

Written by Nathaniel Hansford
Last updated by Elizabeth Reenstra and Pamela Aitchison on 2024/05/15


Darch, C., Eaves, R. C., Crowe, D. A., Simmons, K., & Conniff, A. (2006). Teaching spelling to students with learning disabilities: A comparison of rule-based strategies versus traditional instruction. Journal of Direct Instruction, 6(1), 1–16.


Darch, C., & Simpson, R. G. (1990). Effectiveness of visual imagery versus rule-based strategies in teaching spelling to learning disabled students. Research in Rural Education, 7(1), 61–70.

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