3-人教新课标数学七年级《平行线的特征》教学设计.doc

1、measures planned implementation of technical protection measures and security schemes, the problems should be promptly reported to the Manager. 37th: carbon supervisor leadership and head of the company should periodically check the anti-accident measures planned, security technology protection meas

2、ures planned in implementation of measures against accidents and guarantee schemes, security technology protection measures planned in implementation. Seventh article 38th of education and training: new factory (company) production staff (including internships, commissioned officer), must be approve

3、d by the factory (company), workshop and team level safety education upon passing the examination before entering production site. Tertiary-level education after card registration, by the companys production technology section recovery archive, and reported to the company trade unions, safety record

4、. Training and examinations including the safe work procedures as well as relevant safety regulations, work environment and jobs there are risk factors, preventive measures and emergency treatment, and so on. The 39th article: new producers must receive the following training and qualified posts: (a

5、) the operating personnel, scheduling, must pass through the field point, institutional learning, on-site training and classes practice; (B) the maintenance, including technical staff, must undergo maintenance, technical specifications for learning and class practice; (C) special operations personne

6、l, must pass the national professional training, after obtaining a special operations qualifications before they can post. 40th: on-the-job training of production personnel: (I) post production staff should regularly carry out targeted of technical questions and answers, an accident expected on site

7、 training and anti-accident; (B) from running post 1 month and above the main post on duty or leave transportation . Drive system and security studies, arranged by upper management or organization of the examination. The 42nd article: June of every year once regulatory and safety procedures of the c

8、ompany system of examinations, examination the failed again, still not eligible waiting list study. Article 43rd: every year in June the work ticket issuer, assignee, licensee of work training, after passing the examination, as a formal announcement are eligible to work as ticket issuer, head of ins

9、pection, work permits and the right to a separate high-pressure equipment list, and reported to the Management Department. Failing the exam may not serve as a two person, stop classes, examinations before they can post. 44th: for breach of discipline system caused the accident, a kind of disorder an

10、d attempted serious responsibility for the accident, in addition to the relevant provisions dealing with should also be tasked to learn about a point system, and after passing the exam, before they can post. Article 45th: units of the company using the security video, slide projector, television, co

11、mputer, multimedia, radio, Billboard, artifacts, photo exhibitions, as well as security knowledge exam, lectures, contests, and other forms of advocacy, popularize the knowledge of security technology, targeted, Visual training, enhancing workers safety awareness and self-protection ability. Article

12、 46th平行线的特征一、教学目标(一)知识目标1.平行线的性质2.运用这些性质进行简单的推理或计算.(二)能力目标1.经历观察、操作、推理、交流等活动，进一步发展空间观念、推理能力和有条理表达的能力.2.经历探索平行线的特征的过程，掌握平行线的特征，并能解决一些问题.(三)情感目标通过学生动手操作、观察，来发展他们的空间观念，培养其主动探索和合作的能力.二、教学重难点（一）教学重点由两直线平行得到同位角相等、内错角相等、同旁内角互补.（二）教学难点平行线的特征与直线平行的条件的综合应用.三、教具准备制作电脑动画来说明平行线的特征.投影片五张第一张：P59的问题(1)(记作投影片2.3 A)第

13、二张：P59的问题(2)、(3)(记作投影片2.3 B)第三张：平行线的特征(记作投影片2.3 C)第四张：做一做(记作投影片2.3 D)第五张：小华的思考(记作投影片2.3 E)四、教学过程.创设现实情景，引入新课师前面两节课，我们共同探讨了直线平行的条件，哪位同学给大家叙述一下：直线平行的条件呢？生同位角相等，两直线平行.内错角相等，两直线平行.同旁内角互补，两直线平行.师很好.大家来观察上面的三个直线平行的条件的共同点是什么呢？生都是由已知角相等或角互补，推出两直线平行.师同学们总结得很对，那反过来，如果有两条直线平行，那么同位角、内错角、同旁内角各有什么关系呢？这节课我们来学习直线平行

14、的特征.讲授新课师我们来做一做(出示投影片2.3 A)如图236，直线a与直线b平行.图236测量同位角1和5的大小，它们有什么关系？图中还有其他的同位角吗？它们的大小有什么关系？换另一组平行线试试，你能得到相同的结论吗？师大家先画一组平行线，画平行线时要注意准确性，然后进行测量，最后分组讨论.生甲我用量角器量得1的度数与5的度数相等，说明同位角相等.生乙我用剪刀剪下1(或5)，把它贴在5(或1)的上面，观察到这两个角相等.也能说明同位角相等.生丙图中还有其他的同位角.如：2与6；3与7；4与8.经过测量，我们知道这些同位角相等.生丁这样，我们能不能说：同位角相等.生戊不行.不是所有的同位角都

15、相等.如图237中的1与2是同位角，1是65，2是50，它们不相等.图237师同学们讨论得很精彩.那想一想：两条直线在什么情况下，同位角才相等？生齐声两条直线平行时，同位角相等.师是吗？我们再来画一组平行线，来验证一下.(学生动手画图，测量后，教师动画演示，以帮助学生归纳)生我们经验证，知道：两条直线只要平行，那么同位角就相等.师噢，同位角相等是平行线特有的性质，不是凡同位角都相等，只有在两条直线平行的条件下，才相等.这样我们就得到了平行线的特征：同位角相等.在两条直线平行的情况下，同位角相等，那此时内错角关系怎样？同旁内角关系怎样？下面我们再来探索:(出示投影片2.3 B)如图238，直线a

16、与直线b平行.图238(1)图中有几对内错角？它们的大小有什么关系？为什么？(2)图中有几对同旁内角？它们的大小有什么关系？为什么？(3)换另一组平行线试一试，你能得到相同的结论吗？(讨论方法同前)生甲图中有2对内错角，分别是：3与6；4与5.我用量角器测量了一下，得知：3与6相等，4与5也相等.生乙不用测量也可以，因为直线a与直线b平行，3与7是同位角，所以3=7.又因为7与6是对顶角，相等，因此可知3与6相等.4与5也可以这样得出.师乙同学叙述得很好，学以致用，他找到了内错角与同位角的关系，从而得到：内错角相等.即ab3=6.推证如下：接下来，我们来解决第(2)问.生丙图中有2对同旁内角，

17、分别是：3与5；4与6.它们的关系为互补，即:3+5=180,4+6=180.因为：直线a与直线b平行，2与6是同位角，所以2=6.又因为:2+4=180,所以可得：4+6=180.同理也可推证：3+5=180.生丁老师，也可以这样说理由吧：因为:直线a与直线b平行，3与6是内错角，所以3=6,又因为:3+4=180.所以可得:6+4=180.因此可知：两条直线平行，同旁内角互补.师同学们讨论.表达得很好.通过找到同旁内角与同位角或内错角的关系，得到了：两直线平行，同旁内角互补.即：ab4+6=180.推理如下：或: 好，大家现在换另一组平行线试试，能得到相同的结论吗？生齐声能.师很好.同学们

18、来看大屏幕(动画演示两直线平行，内错角相等或同旁内角互补).由此我们得到了平行线的特征.(出示投影片2.3 C)两条平行直线被第三条直线所截，同位角相等，内错角相等，同旁内角互补.简记为：两直线平行，同位角相等.两直线平行，内错角相等.两直线平行，同旁内角互补.如图239，图239ab大家再想一想：你还能探索出平行线的哪些特征?生甲在直线a与直线b平行的情况下，如果直线c与直线a垂直，那么直线c必定与直线b垂直.如图239，ab1=5,当ac时，即1=90,则5也等于90，因此，bc.(教师也可用电脑动画演示)师很好.接下来我们做一做.(出示投影片2.3 D)如图240，一束平行光线AB与DE

19、射向一个水平镜面后被反射，此时1=2,3=4.(1)1、3的大小有什么关系？2与4呢？(2)反射光线BC与EF也平行吗？图240师大家要仔细观察，1与3是什么样的角，2与4呢？用自己的语言叙述.生乙从图中可以看出：1与3是同位角，因为AB与DE是平行的，所以1=3.又因为1=2，3=4，所以可得出2=4.生丙因为2与4是同位角，所以BCEF.师很好.同学们来看小华的思考(出示投影片2.3 E)我是这样想的.(1)ABDE1=32=4(2)2=4BCEF.你能说明每一步的理由吗？与同伴交流一下.生丁(1)的第一步的理由：两直线平行，同位角相等.第二步的理由：等量代换.即由：1=3，1=2，3=4

20、，得出2=4的.生戊(2)的理由：同位角相等，两直线平行.师这个题是平行线的特征与直线平行的条件的综合应用.由两直线平行，得到角的关系用到的是平行线的特征；反过来，由角的关系得到两直线平行，用到的是直线平行的条件.同学们要弄清这两者的区别.下面我们来做练习以巩固平行线的特征.课堂练习(一)课本P60随堂练习1.如图241所示，ABCD，ACBD，分别找出与1相等或互补的角.图241解：如图242，与1相等的角有：3，5，7，9，11，13，15.图242与1互补的角有：2，4，6，8，10，12，14，16.(二)读一读：“测量地球的周长”.课时小结本节课我们主要学习了平行线的特征及其应用，还

21、了解了直线平行的条件与平行线的特征的区别.平行线的特征：两条平行线被第三条直线所截，同位角相等，内错角相等，同旁内角互补.这些特征要掌握，还有一些特征同学们只需了解即可.如：两条平行线中的一条直线与第三条直线垂直，那么另一条直线也与第三条直线垂直.课后作业(一)课本P62习题2.4 1、2、3.(二)1.预习内容：P63642.预习提纲(1)如何利用直尺和圆规作一条线段等于已知线段.(2)了解用尺规作图的语言.活动与探究已知如图243，若BED=B+D，则直线AB与CD平行吗？为什么？图243过程让学生了解：从图中找出能直接判定ABCD的角很困难，这时可从线入手，添加一条直线，即过点E作AB的

22、平行线，然后利用“两条直线都和第三条直线平行，这两条直线互相平行”来推证出ABCD.图244结果过点E作EFAB.BEF=B(两直线平行，内错角相等),又BED=B+D(已知)，BED=BEF+DEF,B+D=BEF+DEF(等量代换)，D=DEF(等式的性质)EFCD(内错角相等，两直线平行)ABCD(平行于同一直线的两直线互相平行)(本题还可改一下：若ABCD，则BED=B+D.)五、板书设计2.3 平行线的特征一、平行线的特征两直线平行如图：ab二、做一做三、课堂练习四、课时小结五、课后作业regular issuance system of internal and external

23、accident cases, organizational learning, analysis and discussion on a regular basis, and educate the persons concerned in a timely manner. 47th article: strengthening the safety of staff, establishing the concept of legalization of production safety, establish a people-oriented concept, three do no

24、harm (dont hurt yourself, no harm to others, not to be hurt). 48th eighth day routine: pre-shift and post-shift monitor organizations, safety assist. Before class: succession (started), combined with shift operation and tasks for better risk analysis, arranged security account considerations. After

25、class: summarizing comment on duty and the security situation, praise good deeds criticism ignored safety, illegal operations and other adverse phenomena, and completes the record. 49th: safety day event organized by the monitor, safety help, workshop leaders and checking activities. Classes (groups

26、) or rotating a safety day event a week, activities to learn more about the superior file and the spirit of the meeting, informed of the accident, analysis of the company, workshop and fewer security incidents, as well as the typical illegal team, analysis of operation environment, there may be a ri

27、sk factor for the main content. 50th: security analysis companies every quarter of a security analysis; shop at least once a month analysis, comprehensive analysis of production trends, sum up lessons learned from and the weakness in safety management, accident prevention measures in the study. Meet

28、ing was chaired by enterprise security responsibility, concerning the participation of Heads of Department, workshop. Formation meeting and made public. 51st: security check for carbon companys periodic and non-periodic safety checks should be carried out. Periodic inspection includes fall and sprin

29、g security checks, security checks should be combined with spring or autumn season characteristics and accident law . 52nd: security analysis companies should all be actively involved in the preparation of security advisories, bulletins, integrated security, analysis of accident law, drawing on lessons learned from. 53rd: the companys safety safety month activities each year according to the Governments requirements and deployment of the group, safety month activities focus on advocacy effor