新人教版四年级下册第八单元《平均数》教学设计

choose the correct meaning; (4) to correct the typos; (5) so the child write words (ABAB, and AABB); (6) in accordance with written words; (7) the complete word, and explain the meaning of the word; (8) collocation; (9) make sentences with the word; (10) the written language as required. (C) the main sentence types (1) complete sentences; (2) write down the meaning of a sentence or expression of thoughts and feelings; (3) write sentences as required; (4) finish malalignment of the sentence; (5) modified sentences. 2, knowledge classification (1) the common conjunctions coordinate: ... ... 一面…… ... 1, to examine the topic, identify problems associated with two 2, analysis, alternative question two is in direct proportion to the amount of the associated relationship is inversely proportional relationship. 3, and set unknown, column proportion type 4, and solutions proportion type 5, and test, wrote answer language plenary, and subject: application problem (1)--simple application problem and composite application problem review content simple application problem composite application problem answers application problem of general steps 1, and figure out meaning--through examines the, find known conditions and by seeking problem 2, and analysis number relationship--analysis known conditions Zhijian, and conditions and problem Zhijian of relationship, determine problem-solving method and problem-solving steps. 3, and column type calculation--lists formula, is out subdivisions 4, and test, and wrote answer--check, and checking, and wrote answers typical application problem 13, and subject: application problem (3)--column equation solutions application problem review content overview problem-solving steps 1, and figure out meaning, find by seeking of unknown and x said 2, and according to meaning find equivalent relationship, lists Equation 3, and solutions equation 4, and test, and wrote answers according to meaning find equivalent relationship of common method 1 , And according to common of number relationship type, established equivalent relationship 2, and according to has learn had of calculation formula, 3, and according to problem in the of focus described sentence from overall Shang determine basic of equivalent relationship 4, and using segment figure, and list method, method analysis number 三、探究结果 ，回顾小结 1、体会平均数的意义。

师：回忆一下，我们学了什么？（预设：平均数） 用自己的话说一说，平均数是一个什么样的数？ (引导学生用自己的话说出求平均数的意义和作用。)

①当个数不同，用总数量比较结果时有失公平，可以用两组数据的平均数来比较。

②平均数能较好的反应出一组数据的总体情况 ③平均数是一个虚拟的数. 2、回顾求平均数的方法。

①把多的瓶子移出来，补给少的，使得每个人的瓶子数量同样多，这种方法叫移多补少。

②用先合后分计算的方法求平均数时，平均数=总数量÷总份数 四、联系实际，拓展应用 1、做一做（课件出示）

学生独立思考解决，指名学生板演并说方法。 2、判一判（课件出示）

指名学生读题，独立思考后判断并说理由。 3、说一说（课件出示） 学生小组交流并汇报。 五、评价反思、感受成功

师；同学们回顾一下本节课学习的内容，说说学到了哪些知识？

choose the correct meaning; (4) to correct the typos; (5) so the child write words (ABAB, and AABB); (6) in accordance with written words; (7) the complete word, and explain the meaning of the word; (8) collocation; (9) make sentences with the word; (10) the written language as required. (C) the main sentence types (1) complete sentences; (2) write down the meaning of a sentence or expression of thoughts and feelings; (3) write sentences as required; (4) finish malalignment of the sentence; (5) modified sentences. 2, knowledge classification (1) the common conjunctions coordinate: ... ... 一面…… ... 1, to examine the topic, identify problems associated with two 2, analysis, alternative question two is in direct proportion to the amount of the associated relationship is inversely proportional relationship. 3, and set unknown, column proportion type 4, and solutions proportion type 5, and test, wrote answer language plenary, and subject: application problem (1)--simple application problem and composite application problem review content simple application problem composite application problem answers application problem of general steps 1, and figure out meaning--through examines the, find known conditions and by seeking problem 2, and analysis number relationship--analysis known conditions Zhijian, and conditions and problem Zhijian of relationship, determine problem-solving method and problem-solving steps. 3, and column type calculation--lists formula, is out subdivisions 4, and test, and wrote answer--check, and checking, and wrote answers typical application problem 13, and subject: application problem (3)--column equation solutions application problem review content overview problem-solving steps 1, and figure out meaning, find by seeking of unknown and x said 2, and according to meaning find equivalent relationship, lists Equation 3, and solutions equation 4, and test, and wrote answers according to meaning find equivalent relationship of common method 1 , And according to common of number relationship type, established equivalent relationship 2, and according to has learn had of calculation formula, 3, and according to problem in the of focus described sentence from overall Shang determine basic of equivalent relationship 4, and using segment figure, and list method, method analysis number引导学生梳理知识，加强对平均数的意义和作用的理解。

1：可以利用移多补少法来求平均数，还可以用先合后分计算的方法来求平均数。

2：我学会了用数据分析、比较等多种方式来解决问题，提高了解决问题的能力。

3：我知道了平均数能较好地反映一组数据的总体情况。 六、实践作业、课后延伸

参照十岁儿童身高正常，测量本班同学的身高，判断一下同学们的身高是否正常。(男生：140cm 女生：141cm) 板书设计：

平均数 求平均数的方法： 移多补少 先合后分 平均数能较好的反应一组数据的整体水平。 男生队 女生队 （19+15+16+20+15）÷5 （18+20+19+19）÷4 =85÷5 =76÷4 =17（个） =19（个） 17＜19 答：女生队的成绩好些。