Effects of Varying Unit Size on Spelling Achievement in Learning Disabled Children

The investigation looked at the degree to which varying the number of spelling words taught relates to the percentage of words spelled correctly by learning disabled children. Sixty-four LD children were divided into three treatment groups that differed only in the number of phonemically irregular spelling words taught (three, four, or five per day) across three days of instruction. Results show that, even with efficient instructional procedures, overloading, higher failure rate, and percentage of transposition spelling errors and greater variance in performance may occur when the number of words presented each day exceeds three. The findings support the notion that LD children, in particular, may be subject to overloading if presented with more material than they may be able to handle.