The purpose of this study was to compare the effects of numbers and sentence structures changes in math word problems. Three fourth graders who had learning difficulties participated in the study. Alternative treatments designs were used to compare the effects of two methods. Various word problem using addition, subtraction, and multiplication were selected. Results showed that all three subjects improved and maintained problem-solving skills when numbers were changed than structures. During the experiment, the subjects solved problems that were changed into low-digit numbers. This method was effective for students with learning difficulties when they solved unchanged problems. However, changing structures seemed to be effective for students who had good comprehension skills. Individual students\' learning traits were discussed.
Key words : math word problems, number change, sentence structure change, underachiever