Abstract: Two instruction methods were used in teaching children of the first and second grades to solve verbal arithmetical problems. The experimental group was instructed with the "contrast method" (the reverse operation of a problem was taught), while the control group with the "successive method" (only one-way operation of a problem was taught). One year of systematic observation indicated that the former method is better than the latter, in that it not only promotes the ability to solve verbal arithmetical problems, but also develops the flexibility of thinking. These experiments revealed two types of difficulties in solving verbal problems. Firstly, the children took only the superficial features and grasped only one or two words in question in the attempt to solve the problems; secondly, they failed to solve the problem because of their limited knowledge and little experience of applying the knowledge in new situations. These difficulties could be overcome by the contrast method of instruction and by increasing the knowledge of the children.

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