本研究依据结构-定向教学原理，在总结传统教学经验与有关研究的基础上，探讨了 小学数学加减运算教学的改革问题。通过对我国现行加减运算教学体制的研究发现，加减运算教学的 目标不明确，体制不稳定，教学成效不高。有关加减运算教学的理论研究也较薄弱，表现为加减运算能力的实质、结构及其形成规律不清，运算与计算相混淆。 本研究依据能力的类化经验说，应用 系统分析法，对加减运算活动及其内在调节机制一-加减运算能力的结构及其形成、发展规律进行了探讨，提出运算是依据集合中已知数和未知数的关系，通过数的组合与分解动作，求得某个集合的未知数的数学活动。加法是由部分数求整体数的一种数的操作; 减法是由整体数求部分数的一种数的操作。加减运算能力是加减运算活动的内在心理调节机制，由概括化和系统化了的加减运算知识和技能组成。加减运算能力的形成和发展必须在加减运算活动中，通过对加减运算知识和技能的掌握及迁移而实现。 加减运算能力的构成是多因素、多层次、多侧面的，小学加减运算教学的任务在于首先通过20以 内加减运算的教学，使学生形成加减运算能力的基本结构，然后通过万以内及多位数加减运算教学，扩展、充实加减运算能力的基本结构，从而形成并完善整教加减运算能力。 本研究依据上述设想，全面改革了传统的加减运算教学体制，提出了以结构化和定向化为指导思想的实验教学体制。为了检验这一实验教学体制的教学成效，设置了实验班与控制班，进行对照实验。 实验结果表明，实验教学体制的成效明显优于传统教学体制，实验经过适当修改，具有普遍推广应用价值。

According to the Structure-Oriented Tedching Theory, based on the sammary of the traditional teaching experiences and the related results of studies, this reseasch probes into the reform of addition and : substraction instruction in primary schools.From the studies about the system of addition and substraction instruction of our nation, the fact has been known that the aim of teaching is unclear, the system is unstable, and the teaching effects are not good. The theory concerned addition and substraction is lacking, which shows the nature, the structure and the devoloping rules of ability of addition and substraction are not clear, and operation is con fused with counting. According to the theory of generalized experiences of ability, and applying system analysis method, after probing into the nature of addi- tion and substraction and the structure and devoloping rules of addi- tion and substraction ability, we put forward that operation is a kind of mathematical activity which based on the relation of known number and unknown rumber and get. the unknown number by making up or dividing numbers in a set. Addition is getting en- tire number from sectional number, and substractionis getting sec- tional number from entire rumber. The ability of addition and substraction is inner adjusting mechanism of activity of and substraction, and it is made up with generalized and systematized knowledge and skill of addition and sabstraction. It must rely on grasping and transfering knowledge and skill of addi- tion and substraction in activities to form and devolop addi- tion and substraction ability . The structure of addition and substraction has many factors, levels and aspccts. The task of addition andsubstraction in- struction in primary schools is shaping the basic structure of addition and substraction ability through addition and substraction instruction within twenty at first, and then expanding the basic structure and consummating addition and substraction ability of whole number through the instruction of addition and substraction within tenthou- sand and many places number. This research, according to the above tentative ideas, has fully reformed the traditional addition and substraction instruction, and put forward the experimental teaching system guided by the structural and oriental ideas. We have set up experimental class and controlled classes as the objects of comparison in order to examine the teach- ing effect of this system. The results of the experiment prove that the experimental teaching system is obviously better than the tranditional one. The exper- iment can be spread widely after some revisions.