The use of morphological knowledge in spelling derived forms by learning-disabled and normal students.

Currently popular systems for classification of spelling words or errors emphasize the learning of phoneme-grapheme correspondences and memorization of irregular words, but do not take into account the morphophonemic nature of the English language. This study is based on the premise that knowledge of the morphological rules of derivational morphology is acquired developmentally and is related to the spelling abilities of both normal and learning-disabled (LD) students. It addresses three issues: 1) how the learning of derivational morphology and the spelling of derived words by LD students compares to that of normal students; 2) whether LD students learn derived forms rulefully; and 3) the extent to which LD and normal students use knowledge of relationships between base and derived forms to spell derived words (e.g. "magic" and "magician"). The results showed that LD ninth graders' knowledge of derivational morphology was equivalent to that of normal sixth graders, following similar patterns of mastery of orthographic and phonological rules, but that their spelling of derived forms was equivalent to that of the fourth graders. Thus, they know more about derivational morphology than they use in spelling. In addition, they were significantly more apt to spell derived words as whole words, without regard for morphemic structure, than even the fourth graders. Nonetheless, most of the LD spelling errors were phonetically acceptable, suggesting that their misspellings cannot be attributed primarily to poor knowledge of phoneme-grapheme correspondences.