问题解决中策略的变化：一项微观发生研究

以30名小学三年级儿童为被试，以一种特殊的方程问题为材料，采用微观发生法，先后进行了5次测查，收集了解题后的口语报告资料，从策略变化的路线、速率、广度、来源以及变化模式的多样性等方面详细探讨了问题解决策略的变化过程。结果发现，在面临新的问题时，被试缺乏相应知识和专门的解题策略，这时以使用多种常规策略以及错误策略为主；此后，当被试建构起对问题的正确表征时，就以使用正确策略为主，甚至发现了非常有技巧性和领域专门性的快捷策略，这时策略的数量明显减少；在面临难度较大的迁移题目时，快捷策略的使用率又降低，而更多借助于常规策略。可见，策略的获得是一个由错误到正确、由多种尝试到选择其一、由一般到专门的演化过程，这主要是一个学生自主建构的过程，当然也受到正式和非正式教育提供的知识的影响。值得说明的是，快捷策略的获得受到问题呈现模式的影响。总是呈现相同题目的单一模式有助于快捷策略的发现，而在混合训练中，插入不同性质的题目会干扰快捷策略的发现；但是，当面临迁移问题时，单一训练相比于混合训练的优势会消失。此外，正确使用常规策略是发现快捷策略的前提。

ACQUISITION AND CHANGE OF STRATEGY IN MATHEMATICAL PROBLEM SOLVING:A MICROGENETIC STUDY

In this study, a microgenetic method was used to obtain the detailed data on the qualitative and quantitative aspects of change, such as the path, rate, breadth, source and variability of cognitive change. In each of the five testing sessions the data of solution time and accuracy and verbal report on strategies for solving mathematical equivalence problems were collected from 30 3rd-grade children. The results showed that because of having no knowledge base and special strategies for solving new problems participants had to use many general strategies (such as add subtract or equalize), moreover they also had to use many incorrect strategies (such as add all or add to equal sign). Then when they constructed correct representation of problems, they mainly used correct strategies, and they could discover domain special shortcut strategies. At this stage, the variability of strategy decreased. Once they confronted hard transfer task, the proportion of using shortcut strategy cut down significantly, and they had to use general or incorrect strategies. That is to say, at this stage the variability of strategy increased. So it could be concluded that the acquisition of strategies is an evolution process from using incorrect strategies to the correct, from tentatively using many strategies to using only one, from using domain general strategies to using domain special shortcut strategy. The process is a constructive one, but it might be affected by knowledge presented by formal or informal instruction. It was worth paying attention to that the patterns of exercise have effect on the acquisition of shortcut strategy. The blocked problems led to higher levels of activation and discovery of the shortcut strategy than the mixed problems. But the latter is more facilitated to the transfer of shortcut strategy than the former.