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1、名师精编优秀教案思考：还有哪些可能 情 形?你 能 把 问题补充完整吗?有理数的加法教学目的和要求：1使学生了解有理数加法的意义。2使学生理解有理数加法的法则，能熟练地进行有理数加法运算。3培养 学生分析问题、解决问题的能力，在有理数加法法则的教学过程中，注意培养学生的观察、比较、归纳及运算能力。（在教学中适当渗透分类讨论思想）教学重点和难点：重点：有理数加法法则。难点：异号两数相加的法则。教学工具和方法：工具：应用投影仪，投影片。方法：分层次教学，讲授、练习相结合。（采取合作探究式教学方法，让学生在合作学习中学习知识，掌握方法。）教学过程：一、复习引入：1在小学里，已经学过了正整数、正分数（
2、包括正小数）及数0 的四则运算。现在引入了负数，数的范围扩充到了有理数。那么，如何进行有理数的运算呢？2问题：一位同学沿着一条东西向的跑道，先走了 20 米，又走了 30 米，能否确定他现在位于原来位置的哪个方向，相距多少米?我们知道，求两次运动的总结果，可以用加法来解答。可是上述问题不能得到确定答案，因为问题中并未指出行走方向。（大部分同学都会用小学学过的的知识来完成。先给予肯定，鼓励同学们对小学知识的掌握程度，再鼓励同学们想想还有没有其他情况）二、讲授新课：1发现、总结（分类）：我们必须把问题说得明确些，并规定向东为正，向西为负。（同号两数相加法则）(1)若两次都是向东走，很明显，一共向东
3、走了 50 米，写成算式就是：(+20)+(+30)=+50，即这位同学位于原来位置的东方50 米处。这一运算在数轴上表示如图：(2)若两次都是向西走，则他现在位于原来位置的西方50米处，写成算式就是：(20)+(30)=50。（师生共同归纳同号两数相加法则：同号两数相加，取相同的符号，并把绝对值相加）（异号两数相加法则）名师精编优秀教案很重要！(3)若第一次向东走20 米，第二次向西走30 米，我们先在数轴上表示如图：写成算式是(+20)+(30)=10，即这位同学位于原来位置的西方10 米处。(4)若第一次向西走20 米，第二次向东走30 米，写成算式是：(20)+(+30)=()。即这位
4、同学位于原来位置的()方()米处。后两种情形中两个加数符号不同(通常可称异号)，所得和的符号似乎不能确定，让我们再试几 次(下式中的加数不仿仍可看作运动的方向和路程)：你能发现和与两个加数的符号和绝对值之间有什么关系吗?(+4)+(3)=()；(+3)+(10)=()；(5)+(+7)=()；(6)+2=()。再看两种特殊情形：(5)第一次向西走了30 米，第二次向东走了30 米.写成算式是：(30)+(+30)=()。(6)第一次向西走了30 米，第二次没走.写成算式是：(30)+0=()。我们不难 得出它们的结果。（师生共同归纳异号两数相加法则：绝对值不等的异号两数相加，取绝对值较大加数的
5、符号，并用较大的绝对值减去较小的绝对值）（互为相反数的两数相加为零问题：会不会出现和为0 的情况？(5)第一次向西走了30 米，第二次向东走了30 米.写成算式是：(30)+(+30)=()。师生共同归纳法则3：互为相反数的两数相加为零）问题：你能有法则来解释法则3吗？学生回答：可以用异号两数相加的法则）（6)第一次向西走了30 米，第二次没走.写成算式是：(30)+0=()。我们不难得出它们的结果。一般地，一个数同零相加，仍得这个数）2概括：综合以上情形，我们得到有理数的加法法则：1.同号两数相加，取相同的符号，并把绝对值相加；2.绝对值不等的异号两数相加，取绝对值较大加数的符号，并用较大的
6、绝对值减去较小的绝对值；3.互为相反数的两个数相加得0；4.一个数同0 相加，仍得这个数.注意：一个有理数由符号和绝对值两部分组成，所以进行加法运算时，必须分别确定和的符号和绝对值.这与小学阶段学习加法运算不同。文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1
7、ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档
8、编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W
9、3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G
10、1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3
11、文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P
12、1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3名师精编优秀教案有理数的加法（1）1有理数加法法则：
13、例 1五分钟测试：3例题：例 1：计算：(+2)+(11)；(+20)+(+12)；32211；(3.4)+4.3。解：解原式=(112)=9；解原式=+(20+12)=+32=32；解原式=612646313221132211；解原式=+(4.3 3.4)=0.9。（4五分钟测试：计算下列各式(+3)+(+7)(10）+(3)(+6)+(5)0+(5)）三、课堂小结：这节课我们从实例出发，经过比较、归纳，得出了有理数加法的法则今后我们经常要用类似的思想方法研究其他问题应用有理数加法法则进行计算时，要同时注意确定“和”的符号，计算“和”的绝对值两件事。（运算的关键：先分类，在按法则运算运算步骤
14、：先确定符号，再计算绝对值注意问 题：要借助数轴来进一步验证有理数的加法法则）四、课堂作业：课本：P18、2，3。板书设计：教学后记：文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G
15、1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3
16、文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P
17、1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J
18、1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7
19、Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N
20、1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3名师精编优秀教案文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3
21、 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1
22、 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文
23、档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1
24、W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1
25、G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y
26、3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3文档编码:CV9A9N1P1W3 HA5F6S10J1G1 ZJ8F6P7G7Y3