ideological and theoretical qualities and practical working ability, and strive to build a contingent of league cadres with positive work style and high quality. Hold a regular meting of the party secretary every fortnightly, arrange the work of the regiment, fedback the student information. Focus on training junior high school, junior high school secretary of the regiment branch to enable them to raise A firm political conviction, diligent and diligent learning spirit and practical and innovative work style.2.5 有理数的加法与减法班级: 姓名: 【学习目标】1.在正确理解省略括号和的形式基础上,熟练地进行加减混合运算;2.在加减混合运算中,能灵活运用运算律简化运算,提高学生的运算能力;3.通过学生参加探究运算律在加减混合运算中作用的数学活动,体会有理数运算中分析和转化的思想方法.【重、难点】重点:熟练地进行加减混合运算;能灵活运用运算律简化运算,提高学生的运算能力.难点:探究运算律在加减混合运算中作用的数学活动,体会有理数运算中分析和转化的思想方法.【学习过程】一、创设情境1.练习 把(-8)-(+4)+(-6)- (-1)写成省略加号的和的形式并说出它们的两种读法: 解:(-8)-(+4)+(-6)-(-1) =(-8)+(-4)+(-6)+(+1) =-8-4-6+1. 读作“负 8、负4、负 6、正 1 的和”,也可读作“-8 减 4 减 6 加 1”. 2.省略加号的加法算式如-8-4-6+1,怎样可使计算简化呢?请同学们独立思考后沟通.二、探究归纳 1.全班沟通:运用加法运算律,先把负数加在一起,而后做一次异号两数相加.如: -8-4-6+1=-18+1……-8、-4、-6 的和为-18;=-17 ……异号两数相加的结果.联想:在有理数加法运算中,通常适当应用加法运算律可使计算简化,有理数的加减混合运算统一成加法后,一般也应注意运算的合理性.三、实践应用 例 8 计算: 解 (1)-24+3.2-16-3.5+0.3 =(-24-16)+(3.2+0.3)-3.5 (加法交换律、结合律)Strengthen the team connection, strengthen the knowledge education among the students (especially the first grade students), and promote the formation of ...