【教学内容】人教版一年级上册第65页。【教前思考】连加连减是在学生学习了10以内加减法口算的基础上学习的,10以内的加减法口算只需一步计算,而连加连减要分两步进行计算,第一步先求前两个加(减)数的和(差)与第三个加数相加(减)。因为学生初次接触连续两步的计算,在计算过程中又往往看不到第一步的得数,所以计算第二步的时候会发生困难。教材中采用了直观形象 【Teaching content】 PEP P.165. [Pre-teaching thinking] Lianlianlian minus students in the study of the addition and subtraction within 10 based on the learning curve, less than 10 addition and subtraction within the mouth only one-step calculation, and even plus and minus points in two steps to be calculated, The first step first seek the first two plus (minus) the sum (difference) with the third plus (minus). Because students first contact with two consecutive calculations, the calculation process often can not see the first step of the number, so the calculation of the second step will be difficult. Textbook used in an intuitive image