众所周知,20以内进位加法是学习加减法乃至乘除法的重要基础知识,是计算中应掌握的基本功。它的算式较多,掌握较难,要求很高,即看到或听到两个一位数的进位加法,能不假思索地说出正确结果,在头脑中形成自动化的计算模式。因此,它既是教学的重点又是难点。突破这一难点的方法,教材通常是采用凑十法。为了教好凑十法,使每个学生都 It is known to all that the carry-on addition within 20 is an important basic knowledge for learning addition and subtraction and multiplication and division, and is a basic skill that should be mastered in the calculation. Its formula is more difficult to master, high demanding, that is, to see or hear two one-digit carry addition, can not say without thinking to the correct results in the mind to form an automated computing model. Therefore, it is both the focus and the difficulty of teaching. Break through this difficult method, textbooks are usually used ten method. In order to teach the ministry ten methods, so that each student