This study is aimed a improving students' word-problem solving ability in rate word problems. In doing so, a computerized tutoring program was developed in which instruction focused on correcting students' comprehension of the structure of the given problem and training focused on activating their knowledge necessary to solve rate word problems. The efficacy of this tutoring program was tested with 84 fifth graders in a pretest-posttest design. The results showed that it worked far word problems which had a decimal smaller than 1 as divisor to look for an unknown reference set. The implication of this work for the design of effective computer-based tutors was also discussed.

Key words: arithmetic word problems, instruction, problem comprehension, knowledge