北师大版数学下册教学教案
文件夹
作为一位兢兢业业的人民教师,常常要写一份优秀的教案,教案是保证教学取得成功、提高教学质量的基本条件。教案书写有哪些要求呢?我们怎样才能写好一篇教案呢?那么下面我就给大家讲一讲教案怎么写才比较好,我们一起来看一看吧。
教材第4~5页例2、例3和练一练及练习一。
1.使学生理解和掌握圆柱体表面积的计算方法,能根据实际情况正确地进行计算,培养学生解决简单的实际问题的能力。让学生认识取近似值的进一法。
2.进一步培养学生观察、分析和推理等思维能力,发展学生的空间观念。
教师准备一个圆柱模型(表面要有可揭下各个部分的一层纸);学生准备一个圆柱体。
掌握圆柱侧面积的计算方法。
能根据实际情况正确地进行计算。
1.复习圆柱的特征。提问:圆柱有什么特征?
2.计算下面圆柱的侧面积(口头列式):
(1)底面周长4.2厘米,高2厘米。
(2)底面直径3厘米,高4厘米。
(3)底面半径1厘米,高3.5厘米。
3.提问:圆柱的一个底面面积怎样计算?
4.引入新课。
我们已经会计算圆柱的侧面积,那么怎样计算圆柱的表面积呢?这节课就学习圆柱的表面积计算,(板书课题)
1.认识表面积计算方法。
(1) 请同学们拿出圆柱来看一看,想一想圆柱的表面包括哪几个部分,然后告诉大家。指名学生拿出圆柱,边指边说明它的表面包括哪几个部分。
(2)教师演示。
出示教具,说明把表面全部展开,看一看得到什么图形,和大家说的对不对。揭下圆柱表面的纸,贴在黑板上,再与圆柱对比说明各个部分,明确圆柱表面包括一个侧面和两个相等的圆。
(3)得出公式。
请同学们看着表面展开的图形说一说,圆柱的表面积应该怎样计算?(板书:圆柱的表面积:侧面积+两个底面积)追问:圆柱的侧面积怎样算?圆柱的一个底面积怎样算?
2.教学例2。
出示例2,学生读题。提问:这道题分哪几步来算?你们会做吗?指名一人板演,其余学生做在练习本上。集体订正,让学生说说每一步的具体含义,是怎样算的。
3.组织练习。
做练一练。指名两人板演,其余学生做在练习本上。集体订正,说说这两题计算时有什么不同的地方,为什么?指出:计算圆柱的表面积,要注意题里的条件,正确列出算式计算。
4.教学例3。
出示例3,学生读题。提问:这道题实际是求什么?这里求表面积与例2有什么不同,为什么?(只要用侧面积加一个底面积)指名学生板演,其余学生做在练习本上。集体订正,追问为什么只加一个底面积。
5.组织练习。
(1)第七页第四题(2)。先小组合作讨论,再书面练习,然后集体订正。
����
�����ì²äµï¿½4��5ò³ï¿½ï¿½2����3����ò»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï°ò»ï¿½ï¿½
����
����1��ê¹ñ§ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä¼ï¿½ï¿½ã·½ï¿½ï¿½ï¿½ï¿½ï¿½ü¸ï¿½ï¿½ï¿½êµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½è·ï¿½ø½ï¿½ï¿½ð¼ï¿½ï¿½ã£¬ï¿½ï¿½ï¿½ï¿½ñ§ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½òµ¥µï¿½êµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ñ§ï¿½ï¿½ï¿½ï¿½ê¶è¡ï¿½ï¿½ï¿½ï¿½öµï¿½ä½ï¿½ò»ï¿½ï¿½ï¿½ï¿½
����2����ò»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ñ§ï¿½ï¿½ï¿½û²ì¡¢ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ë¼î¬ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½õ¹ñ§ï¿½ï¿½ï¿½ä¿õ¼ï¿½ï¿½ï¿½î¡£
����
������ê¦×¼ï¿½ï¿½ò»ï¿½ï¿½ô²ï¿½ï¿½ä£ï¿½ï¿½(����òªï¿½ð¿é½ï¿½ï¿½â¸ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½öµï¿½ò»ï¿½ï¿½ö½)��ñ§ï¿½ï¿½×¼ï¿½ï¿½ò»ï¿½ï¿½ô²ï¿½ï¿½ï¿½å¡£
����
��������ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä¼ï¿½ï¿½ã·½ï¿½ï¿½ï¿½ï¿½
����
�����ü¸ï¿½ï¿½ï¿½êµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½è·ï¿½ø½ï¿½ï¿½ð¼ï¿½ï¿½ã¡£
����
����
����1����ï°ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ê£ï¿½ô²ï¿½ï¿½ï¿½ï¿½ê²ã´ï¿½ï¿½ï¿½ï¿½?
����2����������ô²ï¿½ï¿½ï¿½ä²ï¿½ï¿½ï¿½ï¿½(��í·ï¿½ï¿½ê½)��
����(1)�����ü³ï¿½4��2���ף���2���ס�
����(2)����ö±ï¿½ï¿½3���ף���4���ס�
����(3)����뾶1���ף���3��5���ס�
����3�����ê£ï¿½ô²ï¿½ï¿½ï¿½ï¿½ò»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½?
����4�������â¿î¡ï¿½
���������ñ¾ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ô²ï¿½ï¿½ï¿½ä²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ã´ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ô²ï¿½ï¿½ï¿½ä±ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½?��ú¿î¾ï¿½ñ§ï°ô²ï¿½ï¿½ï¿½ä±ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ã£¬(�������)
����
����1����ê¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ã·½ï¿½ï¿½ï¿½ï¿½
����(1) ��í¬ñ§ï¿½ï¿½ï¿½ã³ï¿½ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ò»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ò»ï¿½ï¿½ô²ï¿½ï¿½ï¿½ä±ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä¼ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ö£ï¿½è»ï¿½ï¿½ï¿½ï¿½ß´ï¿½ò¡ï¿½ö¸ï¿½ï¿½ñ§ï¿½ï¿½ï¿½ã³ï¿½ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ö¸ï¿½ï¿½ëµï¿½ï¿½ï¿½ï¿½ï¿½ä±ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä¼ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ö¡ï¿½
����(2)��ê¦ï¿½ï¿½ê¾ï¿½ï¿½
������ê¾ï¿½ì¾ß£ï¿½ëµï¿½ï¿½ï¿½ñ±ï¿½ï¿½ï¿½è«ï¿½ï¿½õ¹ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ò»ï¿½ï¿½ï¿½ãµï¿½ê²ã´í¼ï¿½î£ï¿½ï¿½í´ï¿½ï¿½ëµï¿½ä¶ô²ï¿½ï¿½ô¡ï¿½ï¿½ï¿½ï¿½ï¿½ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ö½ï¿½ï¿½ï¿½ï¿½ï¿½úºú°ï¿½ï¿½ï£ï¿½ï¿½ï¿½ï¿½ï¿½ô²ï¿½ï¿½ï¿½ô±ï¿½ëµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ö£ï¿½ï¿½ï¿½è·ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ò»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½èµï¿½ô²ï¿½ï¿½
����(3)�ã³ï¿½ï¿½ï¿½ê½ï¿½ï¿½
������í¬ñ§ï¿½ç¿ï¿½ï¿½å±ï¿½ï¿½ï¿½õ¹ï¿½ï¿½ï¿½ï¿½í¼ï¿½ï¿½ëµò»ëµï¿½ï¿½ô²ï¿½ï¿½ï¿½ä±ï¿½ï¿½ï¿½ï¿½ó¦ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½?(���飺ô²ï¿½ï¿½ï¿½ä±ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½+���������)׷�ê£ï¿½ô²ï¿½ï¿½ï¿½ä²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½?ô²ï¿½ï¿½ï¿½ï¿½ò»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½?
����2����ñ§ï¿½ï¿½2��
������ê¾ï¿½ï¿½2��ñ§ï¿½ï¿½ï¿½ï¿½ï¿½â¡£ï¿½ï¿½ï¿½ê£ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä¼ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½?���ç»ï¿½ï¿½ï¿½ï¿½ï¿½?ö¸ï¿½ï¿½ò»ï¿½ë°ï¿½ï¿½ý£ï¿½ï¿½ï¿½ï¿½ï¿½ñ§ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï°ï¿½ï¿½ï¿½ï¡ï¿½ï¿½ï¿½ï¿½å¶©ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ñ§ï¿½ï¿½ëµëµã¿ò»ï¿½ï¿½ï¿½ä¾ï¿½ï¿½åº¬ï¿½å£¬ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä¡ï¿½
����3����ö¯ï¿½ï¿½ï°ï¿½ï¿½
��������ò»ï¿½ï¿½ï¿½ï¿½ö¸ï¿½ï¿½ï¿½ï¿½ï¿½ë°ï¿½ï¿½ý£ï¿½ï¿½ï¿½ï¿½ï¿½ñ§ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï°ï¿½ï¿½ï¿½ï¡ï¿½ï¿½ï¿½ï¿½å¶©ï¿½ï¿½ï¿½ï¿½ëµëµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ê±ï¿½ï¿½ê²ã´ï¿½ï¿½í¬ï¿½äµø·ï¿½ï¿½ï¿½îªê²ã´?ö¸ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ô²ï¿½ï¿½ï¿½ä±ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½òª×¢ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½è·ï¿½ð³ï¿½ï¿½ï¿½ê½ï¿½ï¿½ï¿½ã¡£
����4����ñ§ï¿½ï¿½3��
������ê¾ï¿½ï¿½3��ñ§ï¿½ï¿½ï¿½ï¿½ï¿½â¡£ï¿½ï¿½ï¿½ê£ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½êµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ê²ã´?��������������2��ê²ã´ï¿½ï¿½í¬ï¿½ï¿½îªê²ã´?(ö»òªï¿½ã²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ò»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½)ö¸ï¿½ï¿½ñ§ï¿½ï¿½ï¿½ï¿½ï¿½ý£ï¿½ï¿½ï¿½ï¿½ï¿½ñ§ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï°ï¿½ï¿½ï¿½ï¡ï¿½ï¿½ï¿½ï¿½å¶©ï¿½ï¿½ï¿½ï¿½×·ï¿½ï¿½îªê²ã´ö»ï¿½ï¿½ò»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
����5����ö¯ï¿½ï¿½ï°ï¿½ï¿½
����(1)����ò³ï¿½ï¿½ï¿½ï¿½ï¿½â£¨2������ð¡ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½û£ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï°ï¿½ï¿½è»ï¿½ï¿½ï¿½å¶©ï¿½ï¿½ï¿½ï¿½
教科书8788页。
1、知识技能:探求给定的事物中隐含的规律或变化趋势。
2、数学思考与解决问题: 体会解决问题的基本过程和方法,提高解决问题的能力。
3、情感态度:探索数与数之间、图形与图形之间的规律
探索规律的方法
如何将规律字母化,也就是如何用字母的式子表示规律。
一张很长的纸条和一根绳子
自主学习、小组合作、讲解法、讨论法
师:说一说我们生活中存在着哪些数学规律?
1、出示乘法表
师:我们的乘法表中也有很多的规律,先请你们填完这个乘法表,
你们会填吗?(师指导怎样填),生做在书66页上
填表完后仔细观察,看看你能发现哪些有趣的规律?和同学说说汇报展示
2、找规律,填一填。
师:比一比看谁在两分钟内做得最多?
(1) 2,4,6,8, _____,12, 14,
(2) 1,3,5,7, _____,11,
(3) 8,11,14,17,_____,23,26,
(4) 1,8,27,64, _____,216,
(5) 1,4,9,16,25, _____,49,
(6) 3,6,9,12,_____, 18,21,
(7) 1,3,6,10,15,_____,28,
(8) 6, 1, 8, 3, 10, 5, 12, 7, ( ) , ( ),
学生在回答问题时,要说明填的理由和依据。
师:填什么数?为什么?
师:象这样的数列你认为一般有哪些规律?
展示生活中数学规律,与同学分享(课件)
师:如果不是数列而是图形你还会观察它们的排列规律吗?
1、六(2)班同学在六一国际儿童节按下面的规律在教室里挂上气球。
第20个汽球是什么颜色的?第48个呢?
�����ì¿ï¿½ï¿½ï¿½8788ò³ï¿½ï¿½
����1��öªê¶ï¿½ï¿½ï¿½ü£ï¿½ì½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä¹ï¿½ï¿½é»ï¿½ä»¯ï¿½ï¿½ï¿½æ¡ï¿½
����2����ñ§ë¼ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½â£º ���������ä»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ìºí·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ß½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
����3�����ì¬ï¿½è£ï¿½ì½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ö®ï¿½ä¡¢í¼ï¿½ï¿½ï¿½ï¿½í¼ï¿½ï¿½ö®ï¿½ï¿½ä¹ï¿½ï¿½ï¿½
����ì½ï¿½ï¿½ï¿½ï¿½ï¿½éµä·ï¿½ï¿½ï¿½
������î½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä¸ï¿½ï¿½ï¿½ï¿½ò²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä¸ï¿½ï¿½ê½ï¿½ó±ï¿½ê¾ï¿½ï¿½ï¿½é¡ï¿½
����ò»ï¿½åºü³ï¿½ï¿½ï¿½ö½ï¿½ï¿½ï¿½ï¿½ò»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
��������ñ§ï°ï¿½ï¿½ð¡ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½â·¨ï¿½ï¿½ï¿½ï¿½ï¿½û·ï¿½
����ê¦ï¿½ï¿½ëµò»ëµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ð´ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ð©ï¿½ï¿½ñ§ï¿½ï¿½ï¿½é£ï¿½
����1����ê¾ï¿½ë·ï¿½ï¿½ï¿½
����ê¦ï¿½ï¿½ï¿½ï¿½ï¿½çµä³ë·ï¿½ï¿½ï¿½ï¿½ï¿½ò²ï¿½ðºü¶ï¿½ä¹ï¿½ï¿½é£ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ë·ï¿½ï¿½ï¿½ï¿½ï¿½
�������ç»ï¿½ï¿½ï¿½ï¿½ð£¿£ï¿½ê¦ö¸ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½î£©ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½66ò³ï¿½ï¿½
������������ï¸ï¿½û²ì£¬ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ü·ï¿½ï¿½ï¿½ï¿½ï¿½ð©ï¿½ï¿½è¤ï¿½ä¹ï¿½ï¿½é£ï¿½ï¿½ï¿½í¬ñ§ëµëµï¿½ã±¨õ¹ê¾
����2���ò¹ï¿½ï¿½é£ï¿½ï¿½ï¿½ò»ï¿½î¡£
����ê¦ï¿½ï¿½ï¿½ï¿½ò»ï¿½è¿ï¿½ë����������������ࣿ
������1�� 2��4��6��8�� _____��12�� 14��
������2�� 1��3��5��7�� _____��11��
������3�� 8��11��14��17��_____��23��26��
������4�� 1��8��27��64�� _____��216��
������5�� 1��4��9��16��25�� _____��49��
������6�� 3��6��9��12��_____�� 18��21��
������7�� 1��3��6��10��15��_____��28��
������8�� 6, 1, 8, 3, 10, 5, 12, 7, �� �� , �� ����
����ñ§ï¿½ï¿½ï¿½ú»ø´ï¿½ï¿½ï¿½ï¿½ï¿½ê±ï¿½ï¿½òªëµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½éºï¿½ï¿½ï¿½ï¿½ý¡ï¿½
����ê¦ï¿½ï¿½ï¿½ï¿½ê²ã´ï¿½ï¿½ï¿½ï¿½îªê²ã´ï¿½ï¿½
����ê¦ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½îªò»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ð©ï¿½ï¿½ï¿½é£ï¿½
����õ¹ê¾ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ñ§ï¿½ï¿½ï¿½é£ï¿½ï¿½ï¿½í¬ñ§ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½î¼ï¿½ï¿½ï¿½
����ê¦ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ð¶ï¿½ï¿½ï¿½í¼ï¿½ï¿½ï¿½ã»¹ï¿½ï¿½û²ï¿½ï¿½ï¿½ï¿½çµï¿½ï¿½ï¿½ï¿½ð¹ï¿½ï¿½ï¿½ï¿½ï¿½
����1������2����í¬ñ§ï¿½ï¿½ï¿½ï¿½ò»ï¿½ï¿½ï¿½ê¶ï¿½í¯ï¿½ú°ï¿½ï¿½ï¿½ï¿½ï¿½ä¹ï¿½ï¿½ï¿½ï¿½ú½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
������20��������ê²ã´ï¿½ï¿½é«ï¿½ä£ï¿½ï¿½ï¿½48���ø£ï¿½
在此之前,他们学习了正比例的意义,对“相关联的量”、“成正比例的两个量的变化规律”、“如何判断两个量是否成正比例”已经有了认识,这为学习《反比例的意义》奠定了基础。
1.使学生认识反比例关系的意义,理解、掌握成反比例量的变化规律及其特征,能依据判断两种量成不成反比例关系。
2.进一步培养学生观察、分析、综合和概括等能力,让学生掌握判断两种相关联的量成不成反比例的方法,培养学生判断、推理的能力。
教学重点:认识反比例关系的意义。
教学难点 :掌握成反比例量的变化规律及其特征。
教学过程一、复习导入
1.正比例关系的意义是什么?怎样用字母表示这种关系?
判断两种相关联量成不成正比例的关键是什么?
2.下面哪两种量成正比例关系?为什么?
(1)时间一定,行驶的速度和路程。
(2)数量一定,单价和总价。
3.说一说工作效率、工作时间和工作总量之间的数量关系。(学生回答后老师板书)在什么条件下,其中两种量成正比例?
4.引入新课。
如果工作总量一定,工作效率和工作时间之间会怎样变化呢,变化又有什么规律呢?这两种量又成什么关系呢?这就是今天要学习的反比例关系。(板书课题)
二、教学新课
1.教学例4。
出示例4。让学生计算,在课本上填表,并观察思考能发现什么?点名让学生按学习正比例的方法观察表里内容,相互之间讨论,发现了什么?
点名学生口答讨论的结果,得出:
(1)每天运的吨数和需要的天数是两种相关联的量,(板书:两种相关联的量)需要的天数随着每天运的吨数的变化而变化。
(2)每天运的吨数缩小,需要的天数反而扩大,每天运的吨数扩大,需要的天数反而缩小。
(3)可以看出它们的变化规律是:每天运的吨数和天数的积总是一定的。(板书:每天运的吨数和天数的积一定)因为每天运的吨数和天数的积都是240。提问:这里的240是什么数量?谁能说出这里的数量关系式?想一想,这个式子表示的是什么意思?(板书补充:运的总吨数一定时,每天运的吨数和天数的积一定)
2.教学例5。
出示例5。
按照刚才学习例4的方法,自己学习例5,仔细想想你发现了些什么?学生观察思考后,指名学生口答从表里发现了些什么?再提问:这两种相关联量变化的规律是什么?
(板书:每袋重量和袋数的积一定)
乘积8000是什么数量,这种数量关系用式子怎样表示?
[板书:每袋重量×袋数=糖果总重量(积一定)]这个式子表示什么意思?(把上面板书补充成:糖果总重量一定时,每袋重量和袋数的积一定)
3.概括。
(1)综合例4、例5的共同点。
提问:请你比较一下例4和例5,说一说,这两个例题有什么共同的地方?
(2)概括反比例意义。
例4、例5里两种相关联的量,它们是什么关系的量呢?
像例4、例5里这样两种相关联的量,一种量变化,另一种量也随着变,变化时两种量中相对应的两个数的积一定。这样两种相关联的量就叫做成反比例的量,它们之间的关系叫做反比例关系。
问:两种相关联的量成不成反比例的关键是什么?
(乘积是不是一定)提问:如果用x和y表示两种相关联的量,用k表示它们的乘积,那么上面这种关系式可以怎样写呢?【板书:x×y=k(一定)】指出:这个式子表示两种相关联的量x和y,y随着x的变化而变化,它们的乘积k是一定的。这时就说x和y成反比例关系。所以,两种量成反比例关系,我们就用x×y=k(一定)来表示。
4.具体认识。
(1)提问:例4里有哪两种相关联的量?这两种量成反比例关系吗?为什么,
例5里的两种量成反比例关系吗?为什么?
(2)提问:看两种相关联的量成不成反比例,关键要看什么?
(3)做练习八第4题。
让学生读题思考。指名依次口答题里的问题。[结合板书;每天装配的台数×天数=一批计算机的总台数(一定)]
(4)判断。
现在回过来看开始写的关系式:工作效率×工作时间=工作总量,当工作总量一定时,工作效率和工作时间成什么关系?为什么?指出:根据上面所说的,要知道两个量成不成反比例关系,只要先看这两种量是不是相关联的量,再看两种量变化时乘积是不是一定。如果两种相关联的量变化时乘积一定,它们就是成反比例的量,相互之间的关系就是反比例关系。
三、巩固练习
1. 做“练一练”第l,2,3,4,5题。
指名口答,说说理由。思考时可以引导看数量关系式,说明理由。
2.拓展应用。
3.综合练习
四、课堂小结
这节课学习的是什么内容?反比例关系的意义是什么?用怎样的式子表示x和y这两种相关联的量成反比例?判断两种量是不是成反比例,关键是什么?
五、课堂作业
����
�����ú´ï¿½ö®ç°ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ñ§ï°ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½å£¬ï¿½ô¡ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä±ä»¯ï¿½ï¿½ï¿½é¡ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ð¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ç·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ñ¾ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ê¶ï¿½ï¿½ï¿½ï¿½îªñ§ï°ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½å¡·ï¿½ì¶¨ï¿½ë»ï¿½ï¿½ï¿½ï¿½ï¿½
����
����1��ê¹ñ§ï¿½ï¿½ï¿½ï¿½ê¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ïµï¿½ï¿½ï¿½ï¿½ï¿½å£¬ï¿½ï¿½ï¿½â¡¢ï¿½ï¿½ï¿½õ³é·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä±ä»¯ï¿½ï¿½ï¿½é¼ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ð¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½é²ï¿½ï¿½é·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ïµï¿½ï¿½
����2����ò»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ñ§ï¿½ï¿½ï¿½û²ì¡¢ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ûºïºí¸ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ñ§ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ð¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½é²ï¿½ï¿½é·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ñ§ï¿½ï¿½ï¿½ð¶ï¡ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
����
������ñ§ï¿½øµã£ºï¿½ï¿½ê¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ïµï¿½ï¿½ï¿½ï¿½ï¿½å¡£
������ñ§ï¿½ñµï¿½ �����õ³é·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä±ä»¯ï¿½ï¿½ï¿½é¼ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
������ñ§ï¿½ï¿½ï¿½ï¿½ò»ï¿½ï¿½ï¿½ï¿½ï°ï¿½ï¿½ï¿½ï¿½
����1����������ïµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ê²ã´?��������ä¸ï¿½ï¿½ê¾ï¿½ï¿½ï¿½ö¹ï¿½ïµ?
�����ð¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½é²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä¹ø¼ï¿½ï¿½ï¿½ê²ã´?
����2������������������������ïµ?îªê²ã´?
����(1)ê±ï¿½ï¿½ò»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ê»ï¿½ï¿½ï¿½ù¶èºï¿½â·ï¿½ì¡ï¿½
����(2)����ò»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ûºï¿½ï¿½ü¼û¡ï¿½
����3��ëµò»ëµï¿½ï¿½ï¿½ï¿½ð§ï¿½ê¡ï¿½ï¿½ï¿½ï¿½ï¿½ê±ï¿½ï¿½í¹ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ö®ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ïµï¿½ï¿½(ñ§ï¿½ï¿½ï¿½ø´ï¿½ï¿½ï¿½ï¿½ê¦ï¿½ï¿½ï¿½ï¿½)��ê²ã´ï¿½ï¿½ï¿½ï¿½ï¿½â£ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½?
����4�������â¿î¡ï¿½
���������������ò»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ð§ï¿½êºí¹ï¿½ï¿½ï¿½ê±ï¿½ï¿½ö®ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä»¯ï¿½ø£ï¿½ï¿½ä»¯ï¿½ï¿½ï¿½ï¿½ê²ã´ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½?���������ö³ï¿½ê²ã´ï¿½ï¿½ïµï¿½ï¿½?����ç½ï¿½ï¿½ï¿½òªñ§ï°ï¿½ä·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ïµï¿½ï¿½(�������)
����������ñ§ï¿½â¿ï¿½
����1����ñ§ï¿½ï¿½4��
������ê¾ï¿½ï¿½4����ñ§ï¿½ï¿½ï¿½ï¿½ï¿½ã£¬ï¿½ú¿î±ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½û²ï¿½ë¼ï¿½ï¿½ï¿½ü·ï¿½ï¿½ï¿½ê²ã´?������ñ§ï¿½ï¿½ï¿½ï¿½ñ§ï°ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä·ï¿½ï¿½ï¿½ï¿½û²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ý£ï¿½ï¿½à»¥ö®ï¿½ï¿½ï¿½ï¿½ï¿½û£ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ê²ã´ï¿½ï¿½
��������ñ§ï¿½ï¿½ï¿½ú´ï¿½ï¿½ï¿½ï¿½ûµä½ï¿½ï¿½ï¿½ï¿½ï¿½ã³ï¿½ï¿½ï¿½
����(1)ã¿ï¿½ï¿½ï¿½ëµä¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½òªï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½(���飺�������������)��òªï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ã¿ï¿½ï¿½ï¿½ëµä¶ï¿½ï¿½ï¿½ï¿½ä±ä»¯ï¿½ï¿½ï¿½ä»¯ï¿½ï¿½
����(2)ã¿ï¿½ï¿½ï¿½ëµä¶ï¿½ï¿½ï¿½ï¿½ï¿½ð¡ï¿½ï¿½ï¿½ï¿½òªï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ã¿ï¿½ï¿½ï¿½ëµä¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½òªï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ð¡ï¿½ï¿½
����(3)���ô¿ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½çµä±ä»¯ï¿½ï¿½ï¿½ï¿½ï¿½ç£ï¿½ã¿ï¿½ï¿½ï¿½ëµä¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä»ï¿½ï¿½ï¿½ï¿½ï¿½ò»ï¿½ï¿½ï¿½ä¡ï¿½(���飺ã¿ï¿½ï¿½ï¿½ëµä¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä»ï¿½ò»ï¿½ï¿½)��îªã¿ï¿½ï¿½ï¿½ëµä¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä»ï¿½ï¿½ï¿½ï¿½ï¿½240�����ê£ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½240��ê²ã´ï¿½ï¿½ï¿½ï¿½?ë��ëµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ïµê½?��ò»ï¿½ë£¬ï¿½ï¿½ï¿½ê½ï¿½ó±ï¿½ê¾ï¿½ï¿½ï¿½ï¿½ê²ã´ï¿½ï¿½ë¼?(���鲹�䣺�ëµï¿½ï¿½ü¶ï¿½ï¿½ï¿½ò»ï¿½ï¿½ê±ï¿½ï¿½ã¿ï¿½ï¿½ï¿½ëµä¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä»ï¿½ò»ï¿½ï¿½)
����2����ñ§ï¿½ï¿½5��
������ê¾ï¿½ï¿½5��
�������õ¸õ²ï¿½ñ§ï°ï¿½ï¿½4�ä·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ô¼ï¿½ñ§ï°ï¿½ï¿½5����ï¸ï¿½ï¿½ï¿½ï¿½ï¿½ã·¢ï¿½ï¿½ï¿½ï¿½ð©ê²ã´?ñ§ï¿½ï¿½ï¿½û²ï¿½ë¼ï¿½ï¿½ï¿½ï¿½ö¸ï¿½ï¿½ñ§ï¿½ï¿½ï¿½ú´ï¿½ó±ï¿½ï¿½ï·¢ï¿½ï¿½ï¿½ï¿½ð©ê²ã´ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ê£ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä»¯ï¿½ä¹ï¿½ï¿½ï¿½ï¿½ï¿½ê²ã´?
����(���飺ã¿ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½í´ï¿½ï¿½ï¿½ï¿½ä»ï¿½ò»ï¿½ï¿½)
�����ë»ï¿½8000��ê²ã´ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ïµï¿½ï¿½ê½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ê¾?
����[���飺ã¿ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ç¹ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½(��ò»ï¿½ï¿½)]���ê½ï¿½ó±ï¿½ê¾ê²ã´ï¿½ï¿½ë¼?(��������鲹��é£ï¿½ï¿½ç¹ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ò»ï¿½ï¿½ê±ï¿½ï¿½ã¿ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½í´ï¿½ï¿½ï¿½ï¿½ä»ï¿½ò»ï¿½ï¿½)
����3��������
����(1)�ûºï¿½ï¿½ï¿½4����5�ä¹ï¿½í¬ï¿½ã¡£
�������ê£ï¿½ï¿½ï¿½ï¿½ï¿½è½ï¿½ò»ï¿½ï¿½ï¿½ï¿½4����5��ëµò»ëµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ê²ã´ï¿½ï¿½í¬ï¿½äµø·ï¿½?
����(2)�������������塣
������4����5�����������������������ê²ã´ï¿½ï¿½ïµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½?
��������4����5���������������������ò»ï¿½ï¿½ï¿½ï¿½ï¿½ä»¯ï¿½ï¿½ï¿½ï¿½ò»ï¿½ï¿½ï¿½ï¿½ò²ï¿½ï¿½ï¿½å±ä£¬ï¿½ä»¯ê±ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ó¦ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä»ï¿½ò»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½í½ï¿½ï¿½ï¿½ï¿½é·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ö®ï¿½ï¿½ä¹ï¿½ïµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ïµï¿½ï¿½
�����ê£ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½é²ï¿½ï¿½é·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä¹ø¼ï¿½ï¿½ï¿½ê²ã´?
����(�ë»ï¿½ï¿½ç²ï¿½ï¿½ï¿½ò»ï¿½ï¿½)���ê£ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½x��y��ê¾ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½k��ê¾ï¿½ï¿½ï¿½çµä³ë»ï¿½ï¿½ï¿½ï¿½ï¿½ã´ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ö¹ï¿½ïµê½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ð´ï¿½ï¿½?�����飺x��y=k(ò»ï¿½ï¿½)��ö¸ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ê½ï¿½ó±ï¿½ê¾ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½x��y��y����x�ä±ä»¯ï¿½ï¿½ï¿½ä»¯ï¿½ï¿½ï¿½ï¿½ï¿½çµä³ë»ï¿½k��ò»ï¿½ï¿½ï¿½ä¡ï¿½ï¿½ï¿½ê±ï¿½ï¿½ëµx��y�é·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ïµï¿½ï¿½ï¿½ï¿½ï¿½ô£ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½é·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ïµï¿½ï¿½ï¿½ï¿½ï¿½ç¾ï¿½ï¿½ï¿½x��y=k(ò»ï¿½ï¿½)����ê¾ï¿½ï¿½
����4��������ê¶ï¿½ï¿½
����(1)���ê£ï¿½ï¿½ï¿½4�������������������?���������é·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ïµï¿½ï¿½?îªê²ã´ï¿½ï¿½
������5����������é·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ïµï¿½ï¿½?îªê²ã´?
����(2)���ê£ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½é²ï¿½ï¿½é·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ø¼ï¿½òªï¿½ï¿½ê²ã´?
����(3)����ï°ï¿½ëµï¿½4�⡣
������ñ§ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ë¼ï¿½ï¿½ï¿½ï¿½ö¸ï¿½ï¿½ï¿½ï¿½ï¿½î¿ú´ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½â¡£[��ï°ï¿½ï¿½é£»ã¿ï¿½ï¿½×°ï¿½ï¿½ï¿½ì¨ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ò»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ì¨ï¿½ï¿½(ò»ï¿½ï¿½)]
����(4)�ð¶ï¡ï¿½
�������ú»ø¹ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ê¼ð´ï¿½ä¹ï¿½ïµê½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ð§ï¿½ê¡ï¿½ï¿½ï¿½ï¿½ï¿½ê±ï¿½ï¿½=��������������������ò»ï¿½ï¿½ê±ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ð§ï¿½êºí¹ï¿½ï¿½ï¿½ê±ï¿½ï¿½ï¿½ê²ã´ï¿½ï¿½ïµ?îªê²ã´?ö¸ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ëµï¿½ä£ï¿½òªöªï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½é²ï¿½ï¿½é·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ïµï¿½ï¿½ö»òªï¿½è¿ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ç²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ù¿ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä»¯ê±ï¿½ë»ï¿½ï¿½ç²ï¿½ï¿½ï¿½ò»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä»¯ê±ï¿½ë»ï¿½ò»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ç¾ï¿½ï¿½ç³é·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½à»¥ö®ï¿½ï¿½ä¹ï¿½ïµï¿½ï¿½ï¿½ç·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ïµï¿½ï¿½
��������������ï°
����1�� ������ò»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½l��2��3��4��5�⡣
����ö¸ï¿½ï¿½ï¿½ú´ï¿½ëµëµï¿½ï¿½ï¿½é¡ï¿½ë¼ï¿½ï¿½ê±ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ïµê½ï¿½ï¿½ëµï¿½ï¿½ï¿½ï¿½ï¿½é¡ï¿½
����2����õ¹ó¦ï¿½ã¡ï¿½
����3���ûºï¿½ï¿½ï¿½ï°
�����ä¡ï¿½ï¿½ï¿½ï¿½ï¿½ð¡ï¿½ï¿½
������ú¿ï¿½ñ§ï°ï¿½ï¿½ï¿½ï¿½ê²ã´ï¿½ï¿½ï¿½ï¿½?��������ïµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ê²ã´?��������ê½ï¿½ó±ï¿½ê¾x��y����������������é·ï¿½ï¿½ï¿½ï¿½ï¿½?�ð¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ç²ï¿½ï¿½ç³é·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ø¼ï¿½ï¿½ï¿½ê²ã´?
�����塢������òµ
1、使学生理解求圆锥体积的计算公式.
2、会运用公式计算圆锥的体积.
圆锥体体积计算公式的推导过程.
正确理解圆锥体积计算公式.
1、提问:
(1)圆柱的体积公式是什么?
(2)投影出示圆锥体的图形,学生指图说出圆锥的底面、侧面和高.
2、导入:同学们,前面我们已经认识了圆锥,掌握了它的特征,那么圆锥的体积怎样计算呢?这节课我们就来研究这个问题.(板书:圆锥的体积)
(一)指导探究圆锥体积的计算公式.
1、教师谈话:
下面我们利用实验的方法来探究圆锥体积的计算方法.老师给每组同学都准备了两个圆锥体容器,两个圆柱体容器和一些沙土.实验时,先往圆柱体(或圆锥体)容器里装满沙土(用直尺将多余的沙土刮掉),倒人圆锥体(或圆柱体)容器里.倒的时候要注意,把两个容器比一比、量一量,看它们之间有什么关系,并想一想,通过实验你发现了什么?
2、学生分组实验
3、学生汇报实验结果(课件演示:圆锥体的体积1、2、3、4、5)
①圆柱和圆锥的底面积相等,高不相等,圆锥体容器装满沙土往圆柱体容器里倒,倒了一次,又倒了一些,才装满.
②圆柱和圆锥的底面积不相等,高相等,圆锥体容器装满沙土往圆柱体容器里倒,倒了两次,又倒了一些,才装满.
③圆柱和圆锥的底面积相等,高相等,圆锥体容器装满沙土往圆柱体容器里倒,倒了三次,正好装满.
4、引导学生发现:
圆柱体的体积等于和它等底等高的圆锥体体积的3倍或圆锥的体积是和它等底等高圆柱体积的1/3.
5、推导圆锥的体积公式:
圆锥的体积是和它等底等高圆柱体积的1/3
v=1/3sh
6、思考:要求圆锥的体积,必须知道哪两个条件?
7、反馈练习
圆锥的底面积是5,高是3,体积是()
圆锥的底面积是10,高是9,体积是()
(二)教学例1
1、例1一个圆锥形的零件,底面积是19平方厘米,高是12厘米.这个零件的体积是多少?
学生独立计算,集体订正.
2、反馈练习:一个圆锥的底面积是25平方分米,高是9分米,她它的体积是多少?
3、思考:求圆锥的体积,还可能出现哪些情况?(圆锥的底面积不直接告诉)
(1)已知圆锥的底面半径和高,求体积.
(2)已知圆锥的底面直径和高,求体积.
(3)已知圆锥的底面周长和高,求体积.
4、反馈练习:一个圆锥的底面直径是20厘米,高是8厘米,它的体积体积是多少?
通过本节的学习,你学到了什么知识?(从两个方面谈:圆锥体体积公式的推导方法和公式的应用)
1、求下面各圆锥的体积.
(1)底面面积是7.8平方米,高是1.8米.
(2)底面半径是4厘米,高是21厘米.
(3)底面直径是6分米,高是6分米.
圆柱体的体积等于和它等底等高的圆锥体体积的3倍或圆锥的体积是和它等底等高圆柱体积的1/3.
����
����1��ê¹ñ§ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ô²×¶ï¿½ï¿½ï¿½ï¿½ä¼ï¿½ï¿½ã¹«ê½ï¿½ï¿½
����2�������ã¹ï¿½ê½ï¿½ï¿½ï¿½ï¿½ô²×¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
����
����ô²×¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ã¹«ê½ï¿½ï¿½ï¿½æµï¿½ï¿½ï¿½ï¿½ì£ï¿½
����
������è·ï¿½ï¿½ï¿½ï¿½ô²×¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ã¹«ê½ï¿½ï¿½
����
����
����1�����ê£ï¿½
������1��ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ê½ï¿½ï¿½ê²ã´ï¿½ï¿½
������2��í¶ó°ï¿½ï¿½ê¾ô²×¶ï¿½ï¿½ï¿½í¼ï¿½î£ï¿½ñ§ï¿½ï¿½ö¸í¼ëµï¿½ï¿½ô²×¶ï¿½äµï¿½ï¿½æ¡¢ï¿½ï¿½ï¿½ï¿½í¸ß£ï¿½
����2�����룺í¬ñ§ï¿½ç£ï¿½ç°ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ñ¾ï¿½ï¿½ï¿½ê¶ï¿½ï¿½ô²×¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ã´ô²×¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ø£ï¿½ï¿½ï¿½ú¿ï¿½ï¿½ï¿½ï¿½ç¾ï¿½ï¿½ï¿½ï¿½ð¾ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½â£®ï¿½ï¿½ï¿½ï¿½ï¿½é£ºô²×¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
����
������ò»ï¿½ï¿½ö¸ï¿½ï¿½ì½ï¿½ï¿½ô²×¶ï¿½ï¿½ï¿½ï¿½ä¼ï¿½ï¿½ã¹«ê½ï¿½ï¿½
����1����ê¦ì¸ï¿½ï¿½ï¿½ï¿½
����������������êµï¿½ï¿½ä·ï¿½ï¿½ï¿½ï¿½ï¿½ì½ï¿½ï¿½ô²×¶ï¿½ï¿½ï¿½ï¿½ä¼ï¿½ï¿½ã·½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ê¦ï¿½ï¿½ã¿ï¿½ï¿½í¬ñ§ï¿½ï¿½×¼ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ô²×¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ò»ð©é³ï¿½ï¿½ï¿½ï¿½êµï¿½ï¿½ê±ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ô²ï¿½ï¿½ï¿½å£¨ï¿½ï¿½ô²×¶ï¿½å£©ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½×°ï¿½ï¿½é³ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ö±ï¿½ß½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½é³ï¿½ï¿½ï¿½îµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ô²×¶ï¿½å£¨ï¿½ï¿½ô²ï¿½ï¿½ï¿½å£©ï¿½ï¿½ï¿½ï¿½ï¿½ï£®ï¿½ï¿½ï¿½ï¿½ê±ï¿½ï¿½òª×¢ï¿½â£¬ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ò»ï¿½è¡ï¿½ï¿½ï¿½ò»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ö®ï¿½ï¿½ï¿½ï¿½ê²ã´ï¿½ï¿½ïµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ò»ï¿½ë£¬í¨ï¿½ï¿½êµï¿½ï¿½ï¿½ã·¢ï¿½ï¿½ï¿½ï¿½ê²ã´ï¿½ï¿½
����2��ñ§ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½êµï¿½ï¿½
����3��ñ§ï¿½ï¿½ï¿½ã±¨êµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½î¼ï¿½ï¿½ï¿½ê¾ï¿½ï¿½ô²×¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½1��2��3��4��5��
������ô²ï¿½ï¿½ï¿½ï¿½ô²×¶ï¿½äµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½è£ï¿½ï¿½ß²ï¿½ï¿½ï¿½è£ï¿½ô²×¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½×°ï¿½ï¿½é³ï¿½ï¿½ï¿½ï¿½ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ïµ¹ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ò»ï¿½î£ï¿½ï¿½öµï¿½ï¿½ï¿½ò»ð©ï¿½ï¿½ï¿½ï¿½×°ï¿½ï¿½ï¿½ï¿½
������ô²ï¿½ï¿½ï¿½ï¿½ô²×¶ï¿½äµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½è£ï¿½ï¿½ï¿½ï¿½ï¿½è£ï¿½ô²×¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½×°ï¿½ï¿½é³ï¿½ï¿½ï¿½ï¿½ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ïµ¹ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½î£ï¿½ï¿½öµï¿½ï¿½ï¿½ò»ð©ï¿½ï¿½ï¿½ï¿½×°ï¿½ï¿½ï¿½ï¿½
������ô²ï¿½ï¿½ï¿½ï¿½ô²×¶ï¿½äµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½è£ï¿½ï¿½ï¿½ï¿½ï¿½è£ï¿½ô²×¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½×°ï¿½ï¿½é³ï¿½ï¿½ï¿½ï¿½ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ïµ¹ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½î£ï¿½ï¿½ï¿½ï¿½ï¿½×°ï¿½ï¿½ï¿½ï¿½
����4������ñ§ï¿½ï¿½ï¿½ï¿½ï¿½ö£ï¿½
����ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½úºï¿½ï¿½ï¿½ï¿½èµ×µè¸ßµï¿½ô²×¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½3����ô²×¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½çºï¿½ï¿½ï¿½ï¿½èµ×µè¸ï¿½ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½1/3��
����5���æµï¿½ô²×¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ê½ï¿½ï¿½
����ô²×¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½çºï¿½ï¿½ï¿½ï¿½èµ×µè¸ï¿½ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½1/3
����v=1/3sh
����6��ë¼ï¿½ï¿½ï¿½ï¿½òªï¿½ï¿½ô²×¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½öªï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
����7��������ï°
����ô²×¶ï¿½äµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½5������3������ç£ï¿½ï¿½ï¿½
����ô²×¶ï¿½äµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½10������9������ç£ï¿½ï¿½ï¿½
������������ñ§ï¿½ï¿½1
����1����1ò»ï¿½ï¿½ô²×¶ï¿½îµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½19æ½ï¿½ï¿½ï¿½ï¿½ï¿½×£ï¿½ï¿½ï¿½ï¿½ï¿½12���ף�������������ç¶ï¿½ï¿½ù£ï¿½
����ñ§ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ã£¬ï¿½ï¿½ï¿½å¶©ï¿½ï¿½ï¿½ï¿½
����2��������ï°ï¿½ï¿½ò»ï¿½ï¿½ô²×¶ï¿½äµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½25æ½ï¿½ï¿½ï¿½ï¿½ï¿½×£ï¿½ï¿½ï¿½ï¿½ï¿½9���ף�����������ç¶ï¿½ï¿½ù£ï¿½
����3��ë¼ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ô²×¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ü³ï¿½ï¿½ï¿½ï¿½ï¿½ð©ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ô²×¶ï¿½äµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ö±ï¿½ó¸ï¿½ï¿½ß£ï¿½
������1����öªô²×¶ï¿½äµï¿½ï¿½ï¿½ë¾¶ï¿½í¸ß£ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
������2����öªô²×¶ï¿½äµï¿½ï¿½ï¿½ö±ï¿½ï¿½ï¿½í¸ß£ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
������3����öªô²×¶ï¿½äµï¿½ï¿½ï¿½ï¿½ü³ï¿½ï¿½í¸ß£ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
����4��������ï°ï¿½ï¿½ò»ï¿½ï¿½ô²×¶ï¿½äµï¿½ï¿½ï¿½ö±ï¿½ï¿½ï¿½ï¿½20���ף�����8���ף������������ç¶ï¿½ï¿½ù£ï¿½
����
����í¨ï¿½ï¿½ï¿½ï¿½ï¿½úµï¿½ñ§ï°ï¿½ï¿½ï¿½ï¿½ñ§ï¿½ï¿½ï¿½ï¿½ê²ã´öªê¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ì¸ï¿½ï¿½ô²×¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ê½ï¿½ï¿½ï¿½æµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½í¹ï¿½ê½ï¿½ï¿½ó¦ï¿½ã£ï¿½
����
����1���������ô²×¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
������1�����������7.8æ½ï¿½ï¿½ï¿½×£ï¿½ï¿½ï¿½ï¿½ï¿½1.8�ף�
������2������뾶��4���ף�����21���ף�
������3������ö±ï¿½ï¿½ï¿½ï¿½6���ף�����6���ף�
����
����ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½úºï¿½ï¿½ï¿½ï¿½èµ×µè¸ßµï¿½ô²×¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½3����ô²×¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½çºï¿½ï¿½ï¿½ï¿½èµ×µè¸ï¿½ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½1/3��
通过数学学习活动,使学生学会运用数学的思维方式支解决日常生活中的一些问题,增强应用数学的意识,发展学生的实践能力和创新精神。
知道如何寄信最经济 设计邮票的价值
各类邮票的图片资料
一、复习回顾,揭示课题
1. 观察邮票。
实物投影出示课文中的邮票。
问:你寄过信吗?见过这些邮票吗?
2. 说一说。
(1) 上面这些都是普通邮票,你还见过哪些邮票?
(2) 你知道它们各有什么作用吗?
交流后,使学生明白普通邮票票面值种类齐全,可适用于各种邮政业务。
3. 揭示课题。
师:今天,我们就一起来探究邮票中的数学问题。
板书课题:邮票中的数学问题。
二、新知学习,组织活动
1. 出示邮政相关的费用。
业务种类 计费
单位 资费标准/元
本埠资费 外埠资费
信函 首重100g内,每重20g
(不足20 g按20 g计算) 0.80 1.20
续重101~20xx g每重100 g
(不足100 g按100 g计算) 1.20 2.00
问:从表中你得到哪些信息?
如
(1) 不到20 g的信函,寄给本埠的朋友只要贴0.80元的邮票。
(2) 不到20 g的信函,寄给外埠的朋友要贴1.20元的邮票。
2. 一封45g的信,寄往外地,怎样贴邮票?
(1) 学生观察表中数据,计算出所需邮资。
(2) 说一说你是怎么算的。
想:每重20g,邮资1.20元,40 g的信函,邮资是2.40元。不足20 g按20 g计算,所以45 g的信函,寄往外地所需邮资是3.60元。
3. 如果邮寄不超过100g的信函,最多只能贴3张邮票,只用80分和1.2元的邮票能满足需要吗?如果不能,请你再设计一张邮票,看看多少面值的邮票能满足需要。
(1) 不超过100g的信函,需要多少资费?
①学生说一说各种可能的资费。
②引导列表描述。
1~20、21~40、41~60、61~80、81~100
本埠
外埠
(2) 只用80分和1.2元两种面值可支付的资费是多少?
一张:80分 1.2元
两张:80分2=1.6元 1.22=2.4元 0.8+1.2=2.0元
三张:0.83=2.4元
1.23=3.6元
0.82+1.2=2.8元
1.22+0.8=3.2元
(3) 你认为可以设计一张多少面值的邮票?
①学生自行设计各种面值的邮票。
②看看多少面值的邮票能满足需要。
4. 如果想最多只用4种面值的邮票,就能支付所有不超过400g的信函的资费,除了80分和1.2元两种面值,你认为还需要增加什么面值的邮票?
(1) 先看看从101~400g的信函,有哪些可能的资费。
101~200、201~300、301~400
本埠
外埠
(2) 你想设计什么面值的邮票?
① 自行设计。
② 与同学交流。
(3) 你见到你设计的这种面值的邮票吗?
三、巩固提高
小结 邮票是有益的爱好,可以扩展我们的视野,培养高尚的情操。
����í¨ï¿½ï¿½ï¿½ï¿½ñ§ñ§ï°ï¿½î¶¯ï¿½ï¿½ê¹ñ§ï¿½ï¿½ñ§ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ñ§ï¿½ï¿½ë¼î¬ï¿½ï¿½ê½ö§ï¿½ï¿½ï¿½ï¿½õ³ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ðµï¿½ò»ð©ï¿½ï¿½ï¿½â£¬ï¿½ï¿½ç¿ó¦ï¿½ï¿½ï¿½ï¿½ñ§ï¿½ï¿½ï¿½ï¿½ê¶ï¿½ï¿½ï¿½ï¿½õ¹ñ§ï¿½ï¿½ï¿½ï¿½êµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½í´ï¿½ï¿½â¾ï¿½ï¿½ï¿½
����öªï¿½ï¿½ï¿½ï¿½î¼ï¿½ï¿½ï¿½ï¿½î¾ï¿½ï¿½ �����æ±ï¿½ä¼ï¿½öµ
����������æ±ï¿½ï¿½í¼æ¬ï¿½ï¿½ï¿½ï¿½
����ò»ï¿½ï¿½ï¿½ï¿½ï°ï¿½ø¹ë£ï¿½ï¿½ï¿½ê¾ï¿½ï¿½ï¿½ï¿½
����1�� �û²ï¿½ï¿½ï¿½æ±ï¿½ï¿½
����êµï¿½ï¿½í¶ó°ï¿½ï¿½ê¾ï¿½ï¿½ï¿½ï¿½ï¿½ðµï¿½ï¿½ï¿½æ±ï¿½ï¿½
�����ê£ï¿½ï¿½ï¿½ä¹ï¿½ï¿½ï¿½ï¿½ð£¿¼ï¿½ï¿½ï¿½ï¿½ï¿½ð©ï¿½ï¿½æ±ï¿½ï¿½
����2�� ëµò»ëµï¿½ï¿½
������1�� ������ð©ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½í¨ï¿½ï¿½æ±ï¿½ï¿½ï¿½ã»¹ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ð©ï¿½ï¿½æ±ï¿½ï¿½
������2�� ��öªï¿½ï¿½ï¿½ï¿½ï¿½ç¸ï¿½ï¿½ï¿½ê²ã´ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
����������ê¹ñ§ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½í¨ï¿½ï¿½æ±æ±ï¿½ï¿½öµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½è«ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ú¸ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½òµï¿½ï¿½
����3�� ��ê¾ï¿½ï¿½ï¿½â¡£
����ê¦ï¿½ï¿½ï¿½ï¿½ï¿½ì£¬ï¿½ï¿½ï¿½ç¾ï¿½ò»ï¿½ï¿½ï¿½ï¿½ì½ï¿½ï¿½ï¿½ï¿½æ±ï¿½ðµï¿½ï¿½ï¿½ñ§ï¿½ï¿½ï¿½â¡£
����������⣺��æ±ï¿½ðµï¿½ï¿½ï¿½ñ§ï¿½ï¿½ï¿½â¡£
����������öªñ§ï°ï¿½ï¿½ï¿½ï¿½ö¯ï¿½î¶¯
����1�� ��ê¾ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½øµä·ï¿½ï¿½ã¡ï¿½
����òµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ �æ·ï¿½
ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½î» ï¿½ê·ñ±ï¿½×¼/ôª
���������ê·ï¿½ �Ⲻ�ê·ï¿½
�����åºï¿½ ����100g�ú£ï¿½ã¿ï¿½ï¿½20g
����������20 g��20 g���㣩 0.80 1.20
��������101��20xx gã¿ï¿½ï¿½100 g
����������100 g��100 g���㣩 1.20 2.00
�����ê£ï¿½ï¿½ó±ï¿½ï¿½ï¿½ï¿½ï¿½ãµï¿½ï¿½ï¿½ð©ï¿½ï¿½ï¢ï¿½ï¿½
������
������1�� ����20 g���åºï¿½ï¿½ï¿½ï¿½ä¸ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ö»òªï¿½ï¿½0.80ôªï¿½ï¿½ï¿½ï¿½æ±ï¿½ï¿½
������2�� ����20 g���åºï¿½ï¿½ï¿½ï¿½ä¸ï¿½ï¿½â²ºï¿½ï¿½ï¿½ï¿½ï¿½ï¿½òªï¿½ï¿½1.20ôªï¿½ï¿½ï¿½ï¿½æ±ï¿½ï¿½
����2�� ò»ï¿½ï¿½45g���å£ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ø£ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½æ±ï¿½ï¿½
������1�� ñ§ï¿½ï¿½ï¿½û²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ý£ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ê¡ï¿½
������2�� ëµò»ëµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ã´ï¿½ï¿½ä¡ï¿½
�����룺ã¿ï¿½ï¿½20g������1.20ôªï¿½ï¿½40 g���åºï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½2.40ôªï¿½ï¿½ï¿½ï¿½ï¿½ï¿½20 g��20 g���㣬����45 g���åºï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½3.60ôªï¿½ï¿½
����3�� ����ê¼ä²ï¿½ï¿½ï¿½ï¿½ï¿½100g���åºï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ö»ï¿½ï¿½ï¿½ï¿½3����æ±ï¿½ï¿½ö»ï¿½ï¿½80�öºï¿½1.2ôªï¿½ï¿½ï¿½ï¿½æ±ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½òªï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ü£ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ò»ï¿½ï¿½ï¿½ï¿½æ±ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½öµï¿½ï¿½ï¿½ï¿½æ±ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½òªï¿½ï¿½
������1�� ������100g���åºï¿½ï¿½ï¿½ï¿½ï¿½òªï¿½ï¿½ï¿½ï¿½ï¿½ê·ñ£ï¿½
������ñ§ï¿½ï¿½ëµò»ëµï¿½ï¿½ï¿½ö¿ï¿½ï¿½üµï¿½ï¿½ê·ñ¡ï¿½
�����������ð±ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
����1��20��21��40��41��60��61��80��81��100
��������
�����Ⲻ
������2�� ö»ï¿½ï¿½80�öºï¿½1.2ôªï¿½ï¿½ï¿½ï¿½ï¿½ï¿½öµï¿½ï¿½ö§ï¿½ï¿½ï¿½ï¿½ï¿½ê·ï¿½ï¿½ç¶ï¿½ï¿½ù£ï¿½
����ò»ï¿½å£ï¿½80�� 1.2ôª
�������å£ï¿½80��2=1.6ôª 1.22=2.4ôª 0.8+1.2=2.0ôª
�������å£ï¿½0.83=2.4ôª
����1.23=3.6ôª
����0.82+1.2=2.8ôª
����1.22+0.8=3.2ôª
������3�� ����îªï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ò»ï¿½å¶ï¿½ï¿½ï¿½ï¿½ï¿½öµï¿½ï¿½ï¿½ï¿½æ±ï¿½ï¿½
������ñ§ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½æ¸ï¿½ï¿½ï¿½ï¿½ï¿½öµï¿½ï¿½ï¿½ï¿½æ±ï¿½ï¿½
�����ú¿ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½öµï¿½ï¿½ï¿½ï¿½æ±ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½òªï¿½ï¿½
����4�� ��������ö»ï¿½ï¿½4����öµï¿½ï¿½ï¿½ï¿½æ±ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ö§ï¿½ï¿½ï¿½ï¿½ï¿½ð²ï¿½ï¿½ï¿½ï¿½ï¿½400g���åºï¿½ï¿½ï¿½ï¿½ê·ñ£ï¿½ï¿½ï¿½ï¿½ï¿½80�öºï¿½1.2ôªï¿½ï¿½ï¿½ï¿½ï¿½ï¿½öµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½îªï¿½ï¿½ï¿½ï¿½òªï¿½ï¿½ï¿½ï¿½ê²ã´ï¿½ï¿½öµï¿½ï¿½ï¿½ï¿½æ±ï¿½ï¿½
������1�� �è¿ï¿½ï¿½ï¿½ï¿½ï¿½101��400g���åºï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ð©ï¿½ï¿½ï¿½üµï¿½ï¿½ê·ñ¡ï¿½
����101��200��201��300��301��400
��������
�����Ⲻ
������2�� �������ê²ã´ï¿½ï¿½öµï¿½ï¿½ï¿½ï¿½æ±ï¿½ï¿½
������ ������æ¡ï¿½
������ ��í¬ñ§ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
������3�� ���������æµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½öµï¿½ï¿½ï¿½ï¿½æ±ï¿½ï¿½
���������������
����ð¡ï¿½ï¿½ ��æ±ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä°ï¿½ï¿½ã£ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½õ¹ï¿½ï¿½ï¿½çµï¿½ï¿½ï¿½ò°ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ðµï¿½ï¿½ï¿½ù¡ï¿½
北师大版六年级数学下册93页95页的内容。
1.进一步理解周长、面积、体积等以及相应的单位;
2.沟通几种基本图形面积公式及其推导过程的内在联系,体积计算公式之间的联系,数学知识方法的内在联系,体会转化、类比等数学思想方法,发展初步的推理能力;
3.能正确计算常见平面图形的周长和面积,常见立体图形的表面积和体积,并解决一些简单的实际问题;
4.能综合运用所学过的数学知识和方法解释生活中的现象,解决简单的实际问题。
能正确计算常见平面图形的周长和面积,常见立体图形的表面积和体积
能综合运用所学过的数学知识和方法解释生活中的现象,解决简单的实际问题。
平面图形和立体图形在生活中应用得非常广泛,有时我们要计算它们的面积,体积等,这就需要我们了解一些数据,运用到关于测量的知识,这节课我们就一起来复习图形与测量。(板书课题)
1.长度、面积和体积的认识
(1)我们学校的综合楼准备粉刷和装修,工人叔叔正准备做一些数据的测量,我们也参与到他们中间去,好吗?
(2)大家先想一想,测量哪些地方,会用到什么单位?
问:什么是长度?什么是面积?什么是体积?
2.测量单位及进率
(1)我们知道测量除了数据之外还需要什么呢?现在请同学们回忆一下长度、面积和体积各自的单位,并说出它们之间的进率。
(2)说一说
请大家说一说1米、1分米、1厘米分别有多长,1平方米、1平方分米、1平方厘米、1立方米、1升、1毫升分别有多大?
3.前面我们已经分类复习了平面图形的周长与面积,立体图形的表面积与体积,你最感兴趣的是哪一部分,把它整理出来。
4.汇报交流。交流时要说出每类知识点要注意的问题。
你认为最容易出错的是哪部分内容?有什么好办法避免出错?
����
������ê¦ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ê¼¶ï¿½ï¿½ñ§ï¿½â²ï¿½93ò³95ò³ï¿½ï¿½ï¿½ï¿½ï¿½ý¡ï¿½
����
����1.��ò»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ü³ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ô¼ï¿½ï¿½ï¿½ó¦ï¿½äµï¿½î»ï¿½ï¿½
����2.��í¨ï¿½ï¿½ï¿½ö»ï¿½ï¿½ï¿½í¼ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ê½ï¿½ï¿½ï¿½ï¿½ï¿½æµï¿½ï¿½ï¿½ï¿½ìµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ïµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ã¹«ê½ö®ï¿½ï¿½ï¿½ï¿½ï¿½ïµï¿½ï¿½ï¿½ï¿½ñ§öªê¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ïµï¿½ï¿½ï¿½ï¿½ï¿½×ªï¿½ï¿½ï¿½ï¿½ï¿½ï¿½èµï¿½ï¿½ï¿½ñ§ë¼ï¿½ë·½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½õ¹ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
����3.����è·ï¿½ï¿½ï¿½ã³£ï¿½ï¿½æ½ï¿½ï¿½í¼ï¿½îµï¿½ï¿½ü³ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½í¼ï¿½îµä±ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ò»ð©ï¿½òµ¥µï¿½êµï¿½ï¿½ï¿½ï¿½ï¿½â£»
����4.���ûºï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ñ§ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ñ§öªê¶ï¿½í·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ðµï¿½ï¿½ï¿½ï¿½ó£¬½ï¿½ï¿½ï¿½òµ¥µï¿½êµï¿½ï¿½ï¿½ï¿½ï¿½â¡£
����
��������è·ï¿½ï¿½ï¿½ã³£ï¿½ï¿½æ½ï¿½ï¿½í¼ï¿½îµï¿½ï¿½ü³ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½í¼ï¿½îµä±ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
����
�������ûºï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ñ§ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ñ§öªê¶ï¿½í·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ðµï¿½ï¿½ï¿½ï¿½ó£¬½ï¿½ï¿½ï¿½òµ¥µï¿½êµï¿½ï¿½ï¿½ï¿½ï¿½â¡£
����
����
����æ½ï¿½ï¿½í¼ï¿½îºï¿½ï¿½ï¿½ï¿½ï¿½í¼ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ó¦ï¿½ãµã·ç³ï¿½ï¿½ã·ºï¿½ï¿½ï¿½ï¿½ê±ï¿½ï¿½ï¿½ï¿½òªï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½çµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½è£ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½òªï¿½ï¿½ï¿½ï¿½ï¿½ë½ï¿½ò»ð©ï¿½ï¿½ï¿½ý£ï¿½ï¿½ï¿½ï¿½ãµï¿½ï¿½ï¿½ï¿½ú²ï¿½ï¿½ï¿½ï¿½ï¿½öªê¶ï¿½ï¿½ï¿½ï¿½ú¿ï¿½ï¿½ï¿½ï¿½ç¾ï¿½ò»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï°í¼ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½â£©
����
����1.���è¡ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ê¶
������1������ñ§ð£ï¿½ï¿½ï¿½ûºï¿½â¥×¼ï¿½ï¿½ï¿½ï¿½ë¢ï¿½ï¿½×°ï¿½þ£ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½×¼ï¿½ï¿½ï¿½ï¿½ò»ð©ï¿½ï¿½ï¿½ýµä²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ò²ï¿½ï¿½ï¿½ëµ½ï¿½ï¿½ï¿½ï¿½ï¿½ð¼ï¿½è¥ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
������2���������ò»ï¿½ë£¬ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ð©ï¿½ø·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ãµï¿½ê²ã´ï¿½ï¿½î»ï¿½ï¿½
�����ê£ï¿½ê²ã´ï¿½ç³ï¿½ï¿½è£ï¿½ê²ã´ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ê²ã´ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
����2.������î»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
������1������öªï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ö®ï¿½â»¹ï¿½ï¿½òªê²ã´ï¿½ø£ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½í¬ñ§ï¿½ç»ï¿½ï¿½ï¿½ò»ï¿½â³ï¿½ï¿½è¡ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ôµäµï¿½î»ï¿½ï¿½ï¿½ï¿½ëµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ö®ï¿½ï¿½ä½ï¿½ï¿½ê¡ï¿½
������2��ëµò»ëµ
��������ëµò»ëµ1�ס�1���ס�1���׷ö±ï¿½ï¿½ð¶à³¤ï¿½ï¿½1æ½ï¿½ï¿½ï¿½×¡ï¿½1æ½ï¿½ï¿½ï¿½ï¿½ï¿½×¡ï¿½1æ½ï¿½ï¿½ï¿½ï¿½ï¿½×¡ï¿½1�����ס�1����1�����ö±ï¿½ï¿½ð¶ï¿½ï¿½
����3.ç°ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ñ¾ï¿½ï¿½ï¿½ï¿½à¸´ï°ï¿½ï¿½æ½ï¿½ï¿½í¼ï¿½îµï¿½ï¿½ü³ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½í¼ï¿½îµä±ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½è¤ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ò»ï¿½ï¿½ï¿½ö£ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
����4.�㱨����������ê±òªëµï¿½ï¿½ã¿ï¿½ï¿½öªê¶ï¿½ï¿½òª×¢ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½â¡£
����
��������îªï¿½ï¿½ï¿½ï¿½ï¿½×³ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ý£ï¿½ï¿½ï¿½ê²ã´ï¿½ã°ì·¨ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
引导和培养学生的自主学习能力是切实可行的,对学生养成终身学习的习惯起着不可估量的重要作用。本设计通过让学生找玩具汽车数量与小人书数量之间存在的比例关系和列举比例等,调动学生的学习热情,使学生的学习兴趣和求知欲望得到激发,思维得到拓展。
本设计以扶代讲,巧妙地引导学生主动探究,使学生在解决问题的过程中,不但能理解和掌握解比例的方法,而且能体会到数学与生活的密切联系,使学生的解题能力、合作能力及归纳能力得到提高。
多媒体课件
人类使用货币的历史产生于最早出现物质交换的时代。在原始社会,人们使用“物物交换”的方式交换自己所需要的物资,如用一只羊换一把斧头。我们今天所学的数学知识就从“物物交换”开始。
同学们算一算,14个玩具汽车可以换多少本小人书?
设计意图:通过“物物交换”,激发学生的兴趣,接着呈现“玩具汽车换小人书”这一情境并提出问题,激发学生学习的热情,为探究新知奠定基础。
师:同学们算一算,14个玩具汽车可以换多少本小人书?把你的想法记录在本上。
教师引导学生交流各自的想法,体会在“物物交换”的过程中,玩具汽车的数量与小人书的数量之间存在的关系。
方法一 14÷4=3.5,3.5×10=35(本)。
方法二 10÷2=5,14÷2=7,5×7=35(本)。
方法三 4个玩具汽车=10本小人书,14÷4=3……2,2个玩具汽车=5本小人书,10×3+5=35(本)。
方法四 4个玩具汽车=10本小人书,8个玩具汽车=20本小人书,12个玩具汽车=30本小人书,2个玩具汽车=5本小人书,12+2=14(个),30+5=35(本)。
师:假设14个玩具汽车可以换x本小人书,你能尝试用比例的知识解决问题吗?
方法一 4∶10=14∶x。
方法二 10∶4=x∶14。
方法三 14∶4=x∶10。
方法四 4∶14=10∶x。
生1:根据在比例里,两个内项的积等于两个外项的积,可以把这个比例转化成4x=10×14。
生2:我是这样计算的:
4∶10=14∶x
解:4x=140
x=35
(师巡视,适时指导)
把求出的结果代入比例验算一下,看等式是否成立。
(学生自主验算)
解比例的关键是根据“内项的积等于外项的积”写成等式,再用等式的性质解方程。
设计意图:将解比例的学习融入到问题解决的过程中,引导学生自主独立解决,然后组织学生汇报自己的解法,这样学生对新知识就会更加理解。
����
����
��������������ñ§ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ñ§ï°ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½êµï¿½ï¿½ï¿½ðµä£ï¿½ï¿½ï¿½ñ§ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ñ§ï°ï¿½ï¿½ï°ï¿½ï¿½ï¿½ï¿½ï¿½å²ï¿½ï¿½é¹ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½òªï¿½ï¿½ï¿½ã¡ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½í¨ï¿½ï¿½ï¿½ï¿½ñ§ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ð¡ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ö®ï¿½ï¿½ï¿½ï¿½úµä±ï¿½ï¿½ï¿½ï¿½ï¿½ïµï¿½ï¿½ï¿½ð¾ù±ï¿½ï¿½ï¿½ï¿½è£ï¿½ï¿½ï¿½ï¿½ï¿½ñ§ï¿½ï¿½ï¿½ï¿½ñ§ï°ï¿½ï¿½ï¿½é£¬ê¹ñ§ï¿½ï¿½ï¿½ï¿½ñ§ï°ï¿½ï¿½è¤ï¿½ï¿½ï¿½ï¿½öªï¿½ï¿½ï¿½ï¿½ï¿½ãµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ë¼î¬ï¿½ãµï¿½ï¿½ï¿½õ¹ï¿½ï¿½
����
����������ô·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ñ§ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ì½ï¿½ï¿½ï¿½ï¿½ê¹ñ§ï¿½ï¿½ï¿½ú½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä¹ï¿½ï¿½ï¿½ï¿½ð£ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½õ½ï¿½ï¿½ï¿½ï¿½ï¿½ä·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½áµ½ï¿½ï¿½ñ§ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ïµï¿½ï¿½ê¹ñ§ï¿½ï¿½ï¿½ä½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ãµï¿½ï¿½ï¿½ß¡ï¿½
����
������ã½ï¿½ï¿½î¼ï¿½
����
����
����
��������ê¹ï¿½ã»ï¿½ï¿½òµï¿½ï¿½ï¿½ê·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ê½ï¿½ï¿½ï¿½ï¿½ï¿½ê±ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ôê¼ï¿½ï¿½á£¬ï¿½ï¿½ï¿½ï¿½ê¹ï¿½ã¡ï¿½ï¿½ï¿½ï¿½ï½»ï¿½ï¿½ï¿½ï¿½ï¿½ä·ï¿½ê½ï¿½ï¿½ï¿½ï¿½ï¿½ô¼ï¿½ï¿½ï¿½ï¿½ï¿½òªï¿½ï¿½ï¿½ï¿½ï¿½ê£ï¿½ï¿½ï¿½ï¿½ï¿½ò»ö»ï¿½ï¿½ò»ï¿½ñ¸ï¿½í·ï¿½ï¿½ï¿½ï¿½ï¿½ç½ï¿½ï¿½ï¿½ï¿½ï¿½ñ§ï¿½ï¿½ï¿½ï¿½ñ§öªê¶ï¿½í´ó¡ï¿½ï¿½ï¿½ï¿½ï½»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ê¼ï¿½ï¿½
����
����í¬ñ§ï¿½ï¿½ï¿½ï¿½ò»ï¿½ã£¬14������������ô»ï¿½ï¿½ï¿½ï¿½ù±ï¿½ð¡ï¿½ï¿½ï¿½é£¿
���������í¼ï¿½ï¿½í¨ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï½»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ñ§ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½è¤ï¿½ï¿½ï¿½ï¿½ï¿½å³ï¿½ï¿½ö¡ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ð¡ï¿½ï¿½ï¿½é¡±ï¿½ï¿½ò»ï¿½é¾³ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½â£¬ï¿½ï¿½ï¿½ï¿½ñ§ï¿½ï¿½ñ§ï°ï¿½ï¿½ï¿½ï¿½ï¿½é£¬îªì½ï¿½ï¿½ï¿½ï¿½öªï¿½ì¶¨ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
����
����
����ê¦ï¿½ï¿½í¬ñ§ï¿½ï¿½ï¿½ï¿½ò»ï¿½ã£¬14������������ô»ï¿½ï¿½ï¿½ï¿½ù±ï¿½ð¡ï¿½ï¿½ï¿½é£¿ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ë·¨ï¿½ï¿½â¼ï¿½ú±ï¿½ï¿½ï¡ï¿½
����
������ê¦ï¿½ï¿½ï¿½ï¿½ñ§ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ôµï¿½ï¿½ë·¨ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ú¡ï¿½ï¿½ï¿½ï¿½ï½»ï¿½ï¿½ï¿½ï¿½ï¿½ä¹ï¿½ï¿½ï¿½ï¿½ð£ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ð¡ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ö®ï¿½ï¿½ï¿½ï¿½úµä¹ï¿½ïµï¿½ï¿½
����
��������ò» 14��4��3.5��3.5��10��35(��)��
���������� 10��2��5��14��2��7��5��7��35(��)��
���������� 4�����������10��ð¡ï¿½ï¿½ï¿½é£¬14��4��3����2��2�����������5��ð¡ï¿½ï¿½ï¿½é£¬10��3��5��35(��)��
���������� 4�����������10��ð¡ï¿½ï¿½ï¿½é£¬8�����������20��ð¡ï¿½ï¿½ï¿½é£¬12�����������30��ð¡ï¿½ï¿½ï¿½é£¬2�����������5��ð¡ï¿½ï¿½ï¿½é£¬12��2��14(��)��30��5��35(��)��
����
����
����ê¦ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½14������������ô»ï¿½x��ð¡ï¿½ï¿½ï¿½é£¬ï¿½ï¿½ï¿½ü³ï¿½ï¿½ï¿½ï¿½ã±ï¿½ï¿½ï¿½ï¿½ï¿½öªê¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
����
����
��������ò» 4��10��14��x��
���������� 10��4��x��14��
���������� 14��4��x��10��
���������� 4��14��10��x��
����
����
����
����
������1�������ú±ï¿½ï¿½ï¿½ï¿½ï£¬ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ô°ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½×ªï¿½ï¿½ï¿½ï¿½4x��10��14��
������2��������������ä£ï¿½
����4��10��14��x
�����⣺4x��140
����x��35
����
����(ê¦ñ²ï¿½ó£ï¿½ï¿½ï¿½ê±ö¸ï¿½ï¿½)
����������ä½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ò»ï¿½â£ï¿½ï¿½ï¿½ï¿½ï¿½ê½ï¿½ç·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
����(ñ§ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½)
����
ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä¹ø¼ï¿½ï¿½ç¸ï¿½ï¿½ý¡ï¿½ï¿½ï¿½ï¿½ï¿½ä»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä»ï¿½ï¿½ï¿½ð´ï¿½éµï¿½ê½ï¿½ï¿½ï¿½ï¿½ï¿½ãµï¿½ê½ï¿½ï¿½ï¿½ï¿½ï¿½ê½â·½ï¿½ì¡ï¿½
���������í¼ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ñ§ï°ï¿½ï¿½ï¿½ëµ½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä¹ï¿½ï¿½ï¿½ï¿½ð£ï¿½ï¿½ï¿½ï¿½ï¿½ñ§ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½è»ï¿½ï¿½ï¿½ï¿½ö¯ñ§ï¿½ï¿½ï¿½ã±¨ï¿½ô¼ï¿½ï¿½ä½â·¨ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ñ§ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½öªê¶ï¿½í»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½â¡£
根据教科书自选内容。
1.通过练习,使学生进一步理解并掌握反比例的意义,会正确判断两种相关联的量是否成反比例,并能解决简单的实际问题。
2.进一步培养学生分析问题、解决问题的能力。
3.结合实例,培养学生仔细分析、主动探索的良好的学习习惯。
正确理解反比例的意义,并能作出正确的判断。
能根据反比例的意义,解决相关的实际问题。
1.谈话引入
上节课我们学了什么?今天,我们进行练习(板书:反比例练习)。通过练习,达到以下两个目标:①进一步理解反比例的意义,并能正确判断两个相关联的量是否成反比例;②能根据反比例的意义,解决实际问题。
2.你知道哪些有关反比例的知识
板书:意义、字母表示:xy=k(一定)
1.观察下面三个表
(1)表1中的两种量是怎样变化的?哪种量是一定的?每天烧煤量和烧的天数成什么比例?为什么?
(2)表2中的两种量是怎样变化的?哪种量是一定的?用去的煤和剩下煤的吨数成比例吗?为什么?
(3)表3中的两种量是怎样变化的?哪种量是一定的?平行四边形的底和平行四边形的高成什么比例?为什么?
2.判断
判断下面各题中的两种量是否成比例。如果成比例,成什么比例?
(1)平行四边形的面积一定,它的底和高。
(2)一筐桃平均分给猴子,猴子的只数和每只猴子分的个数。
(3)报纸的单价一定,订阅的份数与总价。
(4)小刚跳高的高度和他的身高。
(5)c=4a
1.巩固练习
一辆汽车从甲地开往乙地,每时行70 km,5时到达。如果要4时到达,每时需要行驶多少千米?
(1)学生读题,理解题意。
(2)会列式解答吗?试试看。还可以怎么解?(引导学生用反比例知识解答)
2.用比例知识解答
(1)同学们做广播操,每行站20人,正好站18行。如果每行站24人,可以站多少行?
(2)用同样的砖铺地,铺18 m2要用618块砖。如果铺24 m2,要用多少块砖?
学生独立分析、解答,教师巡视,并加以指点。
根据这两道题组织学生讨论正比例关系和反比例关系的相同点和不同点。
讨论后全班交流,教师引导学生归纳并板书。
相同点:都有两种相关联的量,一种量变化,另一种量也随着变化。
不同点:正比例是相对应的两个数的比值(商)一定。反比例是相对应的两个数的积一定。
按规律填数。
(1)(1,36),(2,18),(3,12),(4,),(5,)
(2)15,210,315,4(),()25
(3)81,27,(),3,1,()
同学们,今天我们学习了什么?你有什么收获?还有哪些疑问?
根据自己的生活经验,各构建一道生活中用正比例和反比例解决的问题,再解决,并与同学交流你构建问题的思考方法和解决问题的方法。
����
�������ý½ì¿ï¿½ï¿½ï¿½ï¿½ï¿½ñ¡ï¿½ï¿½ï¿½ý¡ï¿½
����
����1��í¨ï¿½ï¿½ï¿½ï¿½ï°ï¿½ï¿½ê¹ñ§ï¿½ï¿½ï¿½ï¿½ò»ï¿½ï¿½ï¿½ï¿½ï¿½â²¢ï¿½ï¿½ï¿½õ·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½å£¬ï¿½ï¿½ï¿½ï¿½è·ï¿½ð¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ç·ï¿½é·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ü½ï¿½ï¿½ï¿½òµ¥µï¿½êµï¿½ï¿½ï¿½ï¿½ï¿½â¡£
����2����ò»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ñ§ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½â¡¢ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
����3�����êµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ñ§ï¿½ï¿½ï¿½ï¿½ï¸ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ì½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ãµï¿½ñ§ï°ï°ï¿½ß¡ï¿½
����
������è·ï¿½ï¿½ï¿½â·´ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½å£¬ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½è·ï¿½ï¿½ï¿½ð¶ï¡ï¿½
����
�����ü¸ï¿½ï¿½ý·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½å£¬ï¿½ï¿½ï¿½ï¿½ï¿½øµï¿½êµï¿½ï¿½ï¿½ï¿½ï¿½â¡£
����
����
����1��ì¸ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
�����ï½ú¿ï¿½ï¿½ï¿½ï¿½ï¿½ñ§ï¿½ï¿½ê²ã´ï¿½ï¿½ï¿½ï¿½ï¿½ì£¬ï¿½ï¿½ï¿½ç½ï¿½ï¿½ï¿½ï¿½ï¿½ï°ï¿½ï¿½ï¿½ï¿½ï¿½é£ºï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï°ï¿½ï¿½ï¿½ï¿½í¨ï¿½ï¿½ï¿½ï¿½ï°ï¿½ï¿½ï¿½ïµ½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä¿ï¿½ê£ºï¿½ù½ï¿½ò»ï¿½ï¿½ï¿½ï¿½ï¿½â·´ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½å£¬ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½è·ï¿½ð¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ç·ï¿½é·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ü¸ï¿½ï¿½ý·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½å£¬ï¿½ï¿½ï¿½êµï¿½ï¿½ï¿½ï¿½ï¿½â¡£
����2����öªï¿½ï¿½ï¿½ï¿½ð©ï¿½ð¹ø·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½öªê¶
�������飺���塢��ä¸ï¿½ï¿½ê¾ï¿½ï¿½xy=k��ò»ï¿½ï¿½ï¿½ï¿½
����
����1���û²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
������1����1�ðµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä»¯ï¿½ä£ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ò»ï¿½ï¿½ï¿½ä£ï¿½ã¿ï¿½ï¿½ï¿½ï¿½ãºï¿½ï¿½ï¿½ï¿½ï¿½õµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ê²ã´ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½îªê²ã´ï¿½ï¿½
������2����2�ðµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä»¯ï¿½ä£ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ò»ï¿½ï¿½ï¿½ä£ï¿½ï¿½ï¿½è¥ï¿½ï¿½ãºï¿½ï¿½ê£ï¿½ï¿½ãºï¿½ä¶ï¿½ï¿½ï¿½ï¿½é±ï¿½ï¿½ï¿½ï¿½ï¿½îªê²ã´ï¿½ï¿½
������3����3�ðµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä»¯ï¿½ä£ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ò»ï¿½ï¿½ï¿½ä£ï¿½æ½ï¿½ï¿½ï¿½ä±ï¿½ï¿½îµäµ×ºï¿½æ½ï¿½ï¿½ï¿½ä±ï¿½ï¿½îµä¸ß³ï¿½ê²ã´ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½îªê²ã´ï¿½ï¿½
����2���ð¶ï¿½
�����ð¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ðµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ç·ï¿½é±ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½é±ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ê²ã´ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
������1��æ½ï¿½ï¿½ï¿½ä±ï¿½ï¿½îµï¿½ï¿½ï¿½ï¿½ò»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½äµ×ºí¸ß¡ï¿½
������2��ò»ï¿½ï¿½ï¿½ï¿½æ½ï¿½ï¿½ï¿½ö¸ï¿½ï¿½ï¿½ï¿½ó£ï¿½ï¿½ï¿½ï¿½óµï¿½ö»ï¿½ï¿½ï¿½ï¿½ã¿ö»ï¿½ï¿½ï¿½ó·öµä¸ï¿½ï¿½ï¿½ï¿½ï¿½
������3����ö½ï¿½äµï¿½ï¿½ï¿½ò»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½äµä·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ü¼û¡ï¿½
������4��ð¡ï¿½ï¿½ï¿½ï¿½ï¿½ßµä¸ß¶èºï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ß¡ï¿½
������5��c=4a
����
����1��������ï°
����ò»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ó¼×µø¿ï¿½ï¿½ï¿½ï¿½òµø£ï¿½ã¿ê±ï¿½ï¿½70 km��5ê±ï¿½ï¿½ï¿½ï¡£ï¿½ï¿½ï¿½òª4ê±ï¿½ï¿½ï¿½ï£¬ã¿ê±ï¿½ï¿½òªï¿½ï¿½ê»ï¿½ï¿½ï¿½ï¿½ç§ï¿½×£ï¿½
����(1)ñ§ï¿½ï¿½ï¿½ï¿½ï¿½â£¬ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½â¡£
����(2)����ê½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ô¿ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ã´ï¿½â£¿ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ñ§ï¿½ï¿½ï¿½ã·ï¿½ï¿½ï¿½ï¿½ï¿½öªê¶ï¿½ï¿½ï¿½
����2���ã±ï¿½ï¿½ï¿½öªê¶ï¿½ï¿½ï¿½
������1��í¬ñ§ï¿½ï¿½ï¿½ï¿½ï¿½ã²¥ï¿½ù£ï¿½ã¿ï¿½ï¿½õ¾20�ë£ï¿½ï¿½ï¿½ï¿½ï¿½õ¾18�ð¡ï¿½ï¿½ï¿½ï¿½ã¿ï¿½ï¿½õ¾24�ë£ï¿½ï¿½ï¿½ï¿½ï¿½õ¾ï¿½ï¿½ï¿½ï¿½ï¿½ð£ï¿½
������2����í¬ï¿½ï¿½ï¿½ï¿½×©ï¿½ìµø£ï¿½ï¿½ï¿½18 m2òªï¿½ï¿½618��ש�������24 m2��òªï¿½ã¶ï¿½ï¿½ù¿ï¿½×©ï¿½ï¿½
����ñ§ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ð£¬½ï¿½ê¦ñ²ï¿½ó£ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ö¸ï¿½ã¡£
������������������ö¯ñ§ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ïµï¿½í·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ïµï¿½ï¿½ï¿½ï¿½í¬ï¿½ï¿½í²ï¿½í¬ï¿½ã¡£
�������ûºï¿½è«ï¿½à½»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ê¦ï¿½ï¿½ï¿½ï¿½ñ§ï¿½ï¿½ï¿½ï¿½ï¿½é²ï¿½ï¿½ï¿½ï¿½é¡£
������í¬ï¿½ã£ºï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ò»ï¿½ï¿½ï¿½ï¿½ï¿½ä»¯ï¿½ï¿½ï¿½ï¿½ò»ï¿½ï¿½ï¿½ï¿½ò²ï¿½ï¿½ï¿½å±ä»¯ï¿½ï¿½
������í¬ï¿½ã£ºï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ó¦ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä±ï¿½öµï¿½ï¿½ï¿½ì£ï¿½ò»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ó¦ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä»ï¿½ò»ï¿½ï¿½ï¿½ï¿½
����
����������������
������1����1��36������2��18������3��12������4��������5����
������2��15��210��315��4()��()25
������3��81��27��������3��1������
����
����í¬ñ§ï¿½ç£ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ñ§ï°ï¿½ï¿½ê²ã´ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ê²ã´ï¿½õ»ñ£¿»ï¿½ï¿½ï¿½ï¿½ï¿½ð©ï¿½ï¿½ï¿½ê£ï¿½
����
���������ô¼ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½î¾ï¿½é£¬ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ò»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½í·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½â£¬ï¿½ù½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½í¬ñ§ï¿½ï¿½ï¿½ï¿½ï¿½ã¹¹ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ë¼ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½í½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä·ï¿½ï¿½ï¿½ï¿½ï¿½
教学目标:使学生认识圆柱的特征,认识圆柱侧面的展开图。
教学准备:教师与学生每人带一个圆柱,教师给学生每4人小组发一个纸制的圆柱。每位学生准备好制作圆柱的材料。
教学重点:使学生认识圆柱的特征。
教学难点:理解圆柱侧面展开是长方形,并理解长与宽与圆柱之间的关系。
教学过程:
我们已经认识了长方体和正方体。
谁能说一说长方体的特征?(长方体是由6个长方形围成的,相对的两个长方形完全相同,长方体的高有无数条。)正方体呢?
谁能说一说我们学习了长方体和正方体的哪些知识?
教师:今天老师和大家一起学习一种新的立体图形:圆柱体,简称圆柱。
1、 初步印象
教师:同学们,请你们用眼睛看,用手摸,说一说圆柱与长方体的有什么不同?
(圆柱是由2个圆,1个曲面围成的。)
2、 小组研究:圆柱的这些面有什么特征呢?面与面之间又有什么联系呢?
3、 交流和汇报
(1)关于两个圆形得出:上下2个圆是完全相等的圆,它们都是圆柱的底面。(2)关于曲面得出:它是圆柱的侧面,如果沿着高展开,可以得到一个长方形或正方形,如果沿着斜线展开可以得到一个平行四边形。展开后的长方形的长相当于圆柱的底面周长,长方形的宽相当于圆柱的高。
(3)关于圆柱的高:两个底面之间的距离叫圆柱的高。高有无数条。高有时也可用长、厚、深代替。
4、 举例说明进一步明确特征
教师:既然大家对圆柱已有了进一步的了解,那么在生活中那些物体是圆柱呢?
(学生举例,再让学生自己判断。当有一个学生说粉笔是圆柱时,教师可让学生进行讨论。)
5、 运用知识进行判断
下面哪些图形是圆柱?哪些不是?说明理由。
6、 制作圆柱
1、 运用知识进行判断
下面哪些图形是圆柱?哪些不是?说明理由。
������ñ§ä¿ï¿½ê£ºê¹ñ§ï¿½ï¿½ï¿½ï¿½ê¶ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ê¶ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½õ¹ï¿½ï¿½í¼ï¿½ï¿½
������ñ§×¼ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ê¦ï¿½ï¿½ñ§ï¿½ï¿½ã¿ï¿½ë´ï¿½ò»ï¿½ï¿½ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ê¦ï¿½ï¿½ñ§ï¿½ï¿½ã¿4��ð¡ï¿½é·¢ò»ï¿½ï¿½ö½ï¿½æµï¿½ô²ï¿½ï¿½ï¿½ï¿½ã¿î»ñ§ï¿½ï¿½×¼ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ô²ï¿½ï¿½ï¿½ä²ï¿½ï¿½ï¡ï¿½
������ñ§ï¿½øµã£ºê¹ñ§ï¿½ï¿½ï¿½ï¿½ê¶ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
������ñ§ï¿½ñµã£ºï¿½ï¿½ï¿½ï¿½ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½õ¹ï¿½ï¿½ï¿½ç³ï¿½ï¿½ï¿½ï¿½î£ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½â³¤ï¿½ï¿½ï¿½ï¿½ï¿½ô²ï¿½ï¿½ö®ï¿½ï¿½ä¹ï¿½ïµï¿½ï¿½
������ñ§ï¿½ï¿½ï¿½ì£ï¿½
���������ñ¾ï¿½ï¿½ï¿½ê¶ï¿½ë³ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½å¡£
����ë��ëµò»ëµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½6��������î§ï¿½éµä£ï¿½ï¿½ï¿½ôµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½è«ï¿½ï¿½í¬ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä¸ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ø£ï¿½
����ë��ëµò»ëµï¿½ï¿½ï¿½ï¿½ñ§ï°ï¿½ë³ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ð©öªê¶ï¿½ï¿½
������ê¦ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ê¦ï¿½í´ï¿½ï¿½ò»ï¿½ï¿½ñ§ï°ò»ï¿½ï¿½ï¿½âµï¿½ï¿½ï¿½ï¿½ï¿½í¼ï¿½î£ï¿½ô²ï¿½ï¿½ï¿½å£¬ï¿½ï¿½ï¿½ô²ï¿½ï¿½ï¿½ï¿½
����1�� ����ó¡ï¿½ï¿½
������ê¦ï¿½ï¿½í¬ñ§ï¿½ç£ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½û¾ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ëµò»ëµô²ï¿½ï¿½ï¿½ë³¤ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ê²ã´ï¿½ï¿½í¬ï¿½ï¿½
������ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½2��ô²ï¿½ï¿½1������î§ï¿½éµä¡ï¿½ï¿½ï¿½
����2�� ð¡ï¿½ï¿½ï¿½ð¾ï¿½ï¿½ï¿½ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ð©ï¿½ï¿½ï¿½ï¿½ê²ã´ï¿½ï¿½ï¿½ï¿½ï¿½ø£ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ö®ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ê²ã´ï¿½ï¿½ïµï¿½ø£ï¿½
����3�� �����í»ã±¨
������1����������ô²ï¿½îµã³ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½2��ô²ï¿½ï¿½ï¿½ï¿½è«ï¿½ï¿½èµï¿½ô²ï¿½ï¿½ï¿½ï¿½ï¿½ç¶ï¿½ï¿½ï¿½ô²ï¿½ï¿½ï¿½äµï¿½ï¿½æ¡£ï¿½ï¿½2����������ã³ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ô²ï¿½ï¿½ï¿½ä²ï¿½ï¿½æ£¬ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½å¸ï¿½õ¹ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ôµãµï¿½ò»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½î»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½î£ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ð±ï¿½ï¿½õ¹ï¿½ï¿½ï¿½ï¿½ï¿½ôµãµï¿½ò»ï¿½ï¿½æ½ï¿½ï¿½ï¿½ä±ï¿½ï¿½î¡ï¿½õ¹ï¿½ï¿½ï¿½ï¿½ä³ï¿½ï¿½ï¿½ï¿½îµä³ï¿½ï¿½àµ±ï¿½ï¿½ô²ï¿½ï¿½ï¿½äµï¿½ï¿½ï¿½ï¿½ü³ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½îµä¿ï¿½ï¿½àµ±ï¿½ï¿½ô²ï¿½ï¿½ï¿½ä¸ß¡ï¿½
������3������ô²ï¿½ï¿½ï¿½ä¸ß£ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ö®ï¿½ï¿½ä¾ï¿½ï¿½ï¿½ï¿½ô²ï¿½ï¿½ï¿½ä¸ß¡ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ê±ò²ï¿½ï¿½ï¿½ã³ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½æ¡£
����4�� ����ëµï¿½ï¿½ï¿½ï¿½ò»ï¿½ï¿½ï¿½ï¿½è·ï¿½ï¿½ï¿½ï¿½
������ê¦ï¿½ï¿½ï¿½ï¿½è»ï¿½ï¿½ò¶ï¿½ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ë½ï¿½ò»ï¿½ï¿½ï¿½ï¿½ï¿½ë½â£¬ï¿½ï¿½ã´ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ð©ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ô²ï¿½ï¿½ï¿½ø£ï¿½
������ñ§ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ñ§ï¿½ï¿½ï¿½ô¼ï¿½ï¿½ð¶ï¡ï¿½ï¿½ï¿½ï¿½ï¿½ò»ï¿½ï¿½ñ§ï¿½ï¿½ëµï¿½û±ï¿½ï¿½ï¿½ô²ï¿½ï¿½ê±ï¿½ï¿½ï¿½ï¿½ê¦ï¿½ï¿½ï¿½ï¿½ñ§ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½û¡ï¿½ï¿½ï¿½
����5�� ����öªê¶ï¿½ï¿½ï¿½ï¿½ï¿½ð¶ï¿½
����������ð©í¼ï¿½ï¿½ï¿½ï¿½ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ð©ï¿½ï¿½ï¿½ç£ï¿½ëµï¿½ï¿½ï¿½ï¿½ï¿½é¡ï¿½
����6�� ����ô²ï¿½ï¿½
����1�� ����öªê¶ï¿½ï¿½ï¿½ï¿½ï¿½ð¶ï¿½
����������ð©í¼ï¿½ï¿½ï¿½ï¿½ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ð©ï¿½ï¿½ï¿½ç£ï¿½ëµï¿½ï¿½ï¿½ï¿½ï¿½é¡ï¿½
1.使学生认识反比例关系的意义,理解、掌握成反比例量的变化规律及其特征,能依据反比例的意义判断两种量成不成反比例关系。
2.进一步培养学生观察、分析、综合和概括等能力,让学生掌握判断两种相关联的量成不成反比例的方法,培养学生判断、推理的能力。
认识反比例关系的意义。
掌握成反比例量的变化规律及其特征。
1.正比例关系的意义是什么?怎样用字母表示这种关系?
判断两种相关联量成不成正比例的关键是什么?
2.下面哪两种量成正比例关系?为什么?
(1)时间一定,行驶的速度和路程。
(2)数量一定,单价和总价。
3.说一说工作效率、工作时间和工作总量之间的数量关系。(学生回答后老师板书)在什么条件下,其中两种量成正比例?
4.引入新课。
如果工作总量一定,工作效率和工作时间之间会怎样变化呢,变化又有什么规律呢?这两种量又成什么关系呢?这就是今天要学习的反比例关系。(板书课题)
1.教学例1。
出示例1某运输公司要运一批300吨的货物。让学生计算并完成填表任务。
每天运的数量(吨) 10 20 30 40 50
所需的天数 30 15 10 7.5
在本上填表,并观察思考能发现什么?指名口答,老师板书填表。让学生按学习正比例的方法观察表里内容,相互之间讨论,发现了什么。
指名学生口答 讨论结果得出:
(1)每天运的吨数和需要的天数是两种相关联的量,(板书:两种相关联的量)需要的天数随着每天运的吨数的变化而变化。
(2)每天运的吨数缩小,需要的天数反而扩大,每天运的吨数扩大,需要的天数反而缩小。
(3)可以看出它们的变化规律是:每天运的吨数和天数的积总是一定的。(板书:每天运的'吨数和天数的积一定)因为每天运的吨数和天数的积都是300。提问:这里的300是什么数量?谁能说出这里的数量关系式?想一想,这个式子表示的是什么意思?(把上面的板书补充成:运的总吨数一定时,每天运的吨数和天数的积一定)
2.教学例2
出示例2
请同学们按照刚才学习例1的方法,自己学习例2,仔细想想你发现了些什么?学生观察思考后,小组讨论:长方形的面积不变,当长发生变化时,长方形的宽发生变化吗?变化的规律是怎样的?
3.概括反比例的意义。
(1)综合例1、例2的共同点。
提问:请你比较一下例1和例2,说一说,这两个例题有什么共同的地方?
(2)概括反比例意义。
例1、例2里两种相关联的量,它们是什么关系的量呢?说明:像例1、例2里这样两种相关联的量,一种量变化,另一种量也随着变,变化时两种量中相对应的两个数的积一定。这样两种相关联的量就叫做成反比例的量,它们之间的关系叫做反比例关系。迫问:两种相关联的量成不成反比例的关键是什么?(乘积是不是一定)提问:如果用x和y表示两种相关联的量,用k表示它们的乘积,那么上面这种关系式可以怎样写呢?(板书:xy=k(一定))指出:这个式子表示两种相关联的量x和y,y随着x的变化而变化,它们的乘积k是一定的。这时就说x和y成反比例关系。所以,两种量成反比例关系,我们就用xy=k(一定)来表示。
4.具体认识。
(1)提问:例1里有哪两种相关联的量?这两种量成反比例关系吗?为什么,
例2里的两种量成反比例关系吗?为什么?
(2)提问:看两种相关联的量成不成反比例,关键要看什么?
(3) 判断。
现在回过来看开始写的关系式:工作效率工作时间=工作总量,当工作总量一定时,工作效率和工作时间成什么关系?为什么?指出:根据上面所说的反比例的意义,要知道两个量成不成反比例关系,只要先看这两种量是不是相关联的量,再看两种量变化时乘积是不是一定。如果两种相关联的量变化时乘积一定,那它们就是成反比例的量,相互之间的关系就是反比例关系。
����1��ê¹ñ§ï¿½ï¿½ï¿½ï¿½ê¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ïµï¿½ï¿½ï¿½ï¿½ï¿½å£¬ï¿½ï¿½ï¿½â¡¢ï¿½ï¿½ï¿½õ³é·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä±ä»¯ï¿½ï¿½ï¿½é¼ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ý·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ð¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½é²ï¿½ï¿½é·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ïµï¿½ï¿½
����2����ò»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ñ§ï¿½ï¿½ï¿½û²ì¡¢ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ûºïºí¸ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ñ§ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ð¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½é²ï¿½ï¿½é·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ñ§ï¿½ï¿½ï¿½ð¶ï¡ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
������ê¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ïµï¿½ï¿½ï¿½ï¿½ï¿½å¡£
�������õ³é·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä±ä»¯ï¿½ï¿½ï¿½é¼ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
����1����������ïµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ê²ã´?��������ä¸ï¿½ï¿½ê¾ï¿½ï¿½ï¿½ö¹ï¿½ïµ?
�����ð¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½é²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä¹ø¼ï¿½ï¿½ï¿½ê²ã´?
����2������������������������ïµ?îªê²ã´?
����(1)ê±ï¿½ï¿½ò»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ê»ï¿½ï¿½ï¿½ù¶èºï¿½â·ï¿½ì¡ï¿½
����(2)����ò»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ûºï¿½ï¿½ü¼û¡ï¿½
����3��ëµò»ëµï¿½ï¿½ï¿½ï¿½ð§ï¿½ê¡ï¿½ï¿½ï¿½ï¿½ï¿½ê±ï¿½ï¿½í¹ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ö®ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ïµï¿½ï¿½(ñ§ï¿½ï¿½ï¿½ø´ï¿½ï¿½ï¿½ï¿½ê¦ï¿½ï¿½ï¿½ï¿½)��ê²ã´ï¿½ï¿½ï¿½ï¿½ï¿½â£ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½?
����4�������â¿î¡ï¿½
���������������ò»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ð§ï¿½êºí¹ï¿½ï¿½ï¿½ê±ï¿½ï¿½ö®ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä»¯ï¿½ø£ï¿½ï¿½ä»¯ï¿½ï¿½ï¿½ï¿½ê²ã´ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½?���������ö³ï¿½ê²ã´ï¿½ï¿½ïµï¿½ï¿½?����ç½ï¿½ï¿½ï¿½òªñ§ï°ï¿½ä·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ïµï¿½ï¿½(�������)
����1����ñ§ï¿½ï¿½1��
������ê¾ï¿½ï¿½1ä³ï¿½ï¿½ï¿½ä¹«ë¾òªï¿½ï¿½ò»ï¿½ï¿½300�öµä»ï¿½ï¿½ï¡£ï¿½ï¿½ñ§ï¿½ï¿½ï¿½ï¿½ï¿½ã²¢ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
����ã¿ï¿½ï¿½ï¿½ëµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ö£ï¿½ 10 20 30 40 50
������������� 30 15 10 7.5
�����ú±ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½û²ï¿½ë¼ï¿½ï¿½ï¿½ü·ï¿½ï¿½ï¿½ê²ã´?ö¸ï¿½ï¿½ï¿½ú´ï¿½ï¿½ï¿½ê¦ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ñ§ï¿½ï¿½ï¿½ï¿½ñ§ï°ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä·ï¿½ï¿½ï¿½ï¿½û²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ý£ï¿½ï¿½à»¥ö®ï¿½ï¿½ï¿½ï¿½ï¿½û£ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ê²ã´ï¿½ï¿½
����ö¸ï¿½ï¿½ñ§ï¿½ï¿½ï¿½ú´ï¿½ ���û½ï¿½ï¿½ï¿½ã³ï¿½ï¿½ï¿½
����(1)ã¿ï¿½ï¿½ï¿½ëµä¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½òªï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½(���飺�������������)��òªï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ã¿ï¿½ï¿½ï¿½ëµä¶ï¿½ï¿½ï¿½ï¿½ä±ä»¯ï¿½ï¿½ï¿½ä»¯ï¿½ï¿½
����(2)ã¿ï¿½ï¿½ï¿½ëµä¶ï¿½ï¿½ï¿½ï¿½ï¿½ð¡ï¿½ï¿½ï¿½ï¿½òªï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ã¿ï¿½ï¿½ï¿½ëµä¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½òªï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ð¡ï¿½ï¿½
����(3)���ô¿ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½çµä±ä»¯ï¿½ï¿½ï¿½ï¿½ï¿½ç£ï¿½ã¿ï¿½ï¿½ï¿½ëµä¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä»ï¿½ï¿½ï¿½ï¿½ï¿½ò»ï¿½ï¿½ï¿½ä¡ï¿½(���飺ã¿ï¿½ï¿½ï¿½ëµï¿½'�����������ä»ï¿½ò»ï¿½ï¿½)��îªã¿ï¿½ï¿½ï¿½ëµä¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä»ï¿½ï¿½ï¿½ï¿½ï¿½300�����ê£ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½300��ê²ã´ï¿½ï¿½ï¿½ï¿½?ë��ëµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ïµê½?��ò»ï¿½ë£¬ï¿½ï¿½ï¿½ê½ï¿½ó±ï¿½ê¾ï¿½ï¿½ï¿½ï¿½ê²ã´ï¿½ï¿½ë¼?(������ä°ï¿½ï¿½é²¹ï¿½ï¿½é£ï¿½ï¿½ëµï¿½ï¿½ü¶ï¿½ï¿½ï¿½ò»ï¿½ï¿½ê±ï¿½ï¿½ã¿ï¿½ï¿½ï¿½ëµä¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä»ï¿½ò»ï¿½ï¿½)
����2����ñ§ï¿½ï¿½2
������ê¾ï¿½ï¿½2
������í¬ñ§ï¿½ç°ï¿½ï¿½õ¸õ²ï¿½ñ§ï°ï¿½ï¿½1�ä·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ô¼ï¿½ñ§ï°ï¿½ï¿½2����ï¸ï¿½ï¿½ï¿½ï¿½ï¿½ã·¢ï¿½ï¿½ï¿½ï¿½ð©ê²ã´?ñ§ï¿½ï¿½ï¿½û²ï¿½ë¼ï¿½ï¿½ï¿½ï¿½ð¡ï¿½ï¿½ï¿½ï¿½ï¿½û£ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½îµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä£¬ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä»¯ê±ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½îµä¿ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä»¯ï¿½ð£¿±ä»¯ï¿½ä¹ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä£ï¿½
����3�����������������塣
����(1)�ûºï¿½ï¿½ï¿½1����2�ä¹ï¿½í¬ï¿½ã¡£
�������ê£ï¿½ï¿½ï¿½ï¿½ï¿½è½ï¿½ò»ï¿½ï¿½ï¿½ï¿½1����2��ëµò»ëµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ê²ã´ï¿½ï¿½í¬ï¿½äµø·ï¿½?
����(2)�������������塣
������1����2�����������������������ê²ã´ï¿½ï¿½ïµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½?ëµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½1����2���������������������ò»ï¿½ï¿½ï¿½ï¿½ï¿½ä»¯ï¿½ï¿½ï¿½ï¿½ò»ï¿½ï¿½ï¿½ï¿½ò²ï¿½ï¿½ï¿½å±ä£¬ï¿½ä»¯ê±ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ó¦ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä»ï¿½ò»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½í½ï¿½ï¿½ï¿½ï¿½é·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ö®ï¿½ï¿½ä¹ï¿½ïµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ïµï¿½ï¿½ï¿½ï¿½ï¿½ê£ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½é²ï¿½ï¿½é·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä¹ø¼ï¿½ï¿½ï¿½ê²ã´?(�ë»ï¿½ï¿½ç²ï¿½ï¿½ï¿½ò»ï¿½ï¿½)���ê£ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½x��y��ê¾ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½k��ê¾ï¿½ï¿½ï¿½çµä³ë»ï¿½ï¿½ï¿½ï¿½ï¿½ã´ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ö¹ï¿½ïµê½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ð´ï¿½ï¿½?�����飺xy=k(ò»ï¿½ï¿½)��ö¸ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ê½ï¿½ó±ï¿½ê¾ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½x��y��y����x�ä±ä»¯ï¿½ï¿½ï¿½ä»¯ï¿½ï¿½ï¿½ï¿½ï¿½çµä³ë»ï¿½k��ò»ï¿½ï¿½ï¿½ä¡ï¿½ï¿½ï¿½ê±ï¿½ï¿½ëµx��y�é·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ïµï¿½ï¿½ï¿½ï¿½ï¿½ô£ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½é·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ïµï¿½ï¿½ï¿½ï¿½ï¿½ç¾ï¿½ï¿½ï¿½xy=k(ò»ï¿½ï¿½)����ê¾ï¿½ï¿½
����4��������ê¶ï¿½ï¿½
����(1)���ê£ï¿½ï¿½ï¿½1�������������������?���������é·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ïµï¿½ï¿½?îªê²ã´ï¿½ï¿½
������2����������é·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ïµï¿½ï¿½?îªê²ã´?
����(2)���ê£ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½é²ï¿½ï¿½é·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ø¼ï¿½òªï¿½ï¿½ê²ã´?
����(3) �ð¶ï¡ï¿½
�������ú»ø¹ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ê¼ð´ï¿½ä¹ï¿½ïµê½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ð§ï¿½ê¹ï¿½ï¿½ï¿½ê±ï¿½ï¿½=��������������������ò»ï¿½ï¿½ê±ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ð§ï¿½êºí¹ï¿½ï¿½ï¿½ê±ï¿½ï¿½ï¿½ê²ã´ï¿½ï¿½ïµ?îªê²ã´?ö¸ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ëµï¿½ä·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½å£¬òªöªï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½é²ï¿½ï¿½é·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ïµï¿½ï¿½ö»òªï¿½è¿ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ç²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ù¿ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä»¯ê±ï¿½ë»ï¿½ï¿½ç²ï¿½ï¿½ï¿½ò»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä»¯ê±ï¿½ë»ï¿½ò»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ç¾ï¿½ï¿½ç³é·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½à»¥ö®ï¿½ï¿½ä¹ï¿½ïµï¿½ï¿½ï¿½ç·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ïµï¿½ï¿½
教材第10~12页圆柱的体积公式,例1、例2和练一练,练习二第1~5题。
1.使学生理解和掌握圆柱的体积计算公式,并能根据题里的条件正确地求出圆柱的体积。
2.培养学生初步的空间观念和思维能力;让学生认识转化的思考方法。
圆柱体积演示教具。
理解和掌握圆柱的体积计算公式。
圆柱体积计算公式的推导。
1.求下面各圆的面积(回答)。
(1)r=1厘米; (2)d=4分米; (3)c=6.28米。
要求说出解题思路。
2.想一想:学习计算圆的面积时,是怎样得出圆的面积计算公式的?指出:把一个圆等分成若干等份,可以拼成一个近似的长方形。这个长方形的面积就是圆的面积。
3.提问:什么叫体积?常用的体积单位有哪些?
4.已知长方体的底面积s和高h,怎样计算长方体的体积?(板书:长方体的体积=底面积高)
1.根据学过的体积概念,说说什么是圆柱的体积。(板书课题)
2.怎样计算圆柱的体积呢?我们能不能根据圆柱的底面可以像上面说的转化成一个长方形,通过切、拼的方法,把圆柱转化为已学过的立体图形来计算呢,现在我们大家一起来讨论。
3.公式推导。(可分小组进行)
(1)请同学指出圆柱体的底面积和高。
(2)回顾圆面积公式的推导。(切拼转化)
(3)探索求圆柱体积的公式。
根据圆面积剪、拼转化成长方形的思路,我们也可以运用切拼转化的方法把圆柱体变成学过的几何形体来推导出圆柱的体积计算公式。你能想出怎样切、拼转化吗?请同学们仔细观察以下实验,边观察边思考圆柱的体积、底面积、高与拼成的几何形体之间的关系。教师演示圆柱体积公式推导演示教具:把圆柱的底面分成许多相等的扇形(数量一般为16个),然后把圆柱切开,照下图拼起来,(图见教材)就近似于一个长方体。可以想象,分成的扇形越多,拼成的立体图形就越接近于长方体。
(4)讨论并得出结果。
你能根据这个实验得出圆柱的体积计算公式吗?为什么?让学生再讨论:圆柱体通过切拼,圆柱体转化成近似的 体。这个长方体的底面积与圆柱体的底面积 ,这个长方体的高与圆柱体的高 。因为长方体的体积等于底面积乘以高,所以,圆柱体的体积计算公式是: 。(板书:圆柱的体积=底面积高)用字母表示: 。(板书:v=sh)
(5)小结。
圆柱的体积是怎样推导出来的?计算圆柱的体积必须知道哪些条件?
4.教学例1。
出示例1,审题。提问:你能独立完成这题吗?指名一同学板演,其余学生做在练习本上。集体订正:列式依据是什么?应注意哪些问题?(单位统一,最后结果用体积单位)
0.9米=90厘米 2490=2160(立方厘米)
5.做练习二第1题。
让学生做在课本上。指名口答,集体订正。追问:圆柱的体积是怎样算的?
6.教学试一试一个圆柱的底面半径是2分米,高是8米,求它的体积。指名一人板演,其余学生做在练习本上。评讲试一试小结:求圆柱的体积,必须知道底面积和高。如果不知道底面积,只知道半径r,通过什么途径求出圆柱的体积?如果知道d呢?知道c呢?知道r、d、c,都要先求出底面积再求体积。
7. 教学例2。
出示例2,审题。小组讨论计算方法,然后学生做在练习本上。集体订正:列式依据是什么?应注意哪些问题?(单位统一,最后结果用体积单位,结果保留整数。)
����
�����ì²äµï¿½10��12ò³ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ê½ï¿½ï¿½ï¿½ï¿½1����2����ò»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï°ï¿½ï¿½ï¿½ï¿½1��5�⡣
����
����1.ê¹ñ§ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ã¹«ê½ï¿½ï¿½ï¿½ï¿½ï¿½ü¸ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½è·ï¿½ï¿½ï¿½ï¿½ï¿½ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
����2.����ñ§ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä¿õ¼ï¿½ï¿½ï¿½ï¿½ï¿½ë¼î¬ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ñ§ï¿½ï¿½ï¿½ï¿½ê¶×ªï¿½ï¿½ï¿½ï¿½ë¼ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
����
����ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ê¾ï¿½ì¾ß¡ï¿½
����
�������������ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ã¹«ê½ï¿½ï¿½
����
����ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ã¹«ê½ï¿½ï¿½ï¿½æµï¿½ï¿½ï¿½
����
����
����1���������ô²ï¿½ï¿½ï¿½ï¿½ï¿½(�ø´ï¿½)��
����(1)r=1���ף� (2)d=4���ף� (3)c=6.28�ס�
����òªï¿½ï¿½ëµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ë¼â·ï¿½ï¿½
����2����ò»ï¿½ë£ºñ§ï°ï¿½ï¿½ï¿½ï¿½ô²ï¿½ï¿½ï¿½ï¿½ï¿½ê±ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ã³ï¿½ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ã¹«ê½ï¿½ï¿½?ö¸ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ò»ï¿½ï¿½ô²ï¿½è·ö³ï¿½ï¿½ï¿½ï¿½éµè·ý£ï¿½ï¿½ï¿½ï¿½ï¿½æ´ï¿½ï¿½ò»ï¿½ï¿½ï¿½ï¿½ï¿½æµä³ï¿½ï¿½ï¿½ï¿½î¡ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½îµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
����3�����ê£ï¿½ê²ã´ï¿½ï¿½ï¿½ï¿½ï¿½?���ãµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½î»ï¿½ï¿½ï¿½ï¿½ð©?
����4����öªï¿½ï¿½ï¿½ï¿½ï¿½ï¿½äµï¿½ï¿½ï¿½ï¿½s�í¸ï¿½h���������㳤��������?(���飺����������=�������)
����
����1������ñ§ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½î£¬ëµëµê²ã´ï¿½ï¿½ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½(�������)
����2����������ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½?�����ü²ï¿½ï¿½ü¸ï¿½ï¿½ï¿½ô²ï¿½ï¿½ï¿½äµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ëµï¿½ï¿½×ªï¿½ï¿½ï¿½ï¿½ò»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½î£ï¿½í¨ï¿½ï¿½ï¿½ð¡ï¿½æ´ï¿½ä·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ô²ï¿½ï¿½×ªï¿½ï¿½îªï¿½ï¿½ñ§ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½í¼ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ø£ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ç´ï¿½ï¿½ò»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½û¡ï¿½
����3����ê½ï¿½æµï¿½ï¿½ï¿½(�é·ï¿½ð¡ï¿½ï¿½ï¿½ï¿½ï¿½)
����(1)��í¬ñ§ö¸ï¿½ï¿½ô²ï¿½ï¿½ï¿½ï¿½äµï¿½ï¿½ï¿½ï¿½ï¿½í¸ß¡ï¿½
����(2)�ø¹ï¿½ô²ï¿½ï¿½ï¿½ï¿½ï¿½ê½ï¿½ï¿½ï¿½æµï¿½ï¿½ï¿½(��æ´×ªï¿½ï¿½)
����(3)ì½ï¿½ï¿½ï¿½ï¿½ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä¹ï¿½ê½ï¿½ï¿½
��������ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½æ´×ªï¿½ï¿½ï¿½é³ï¿½ï¿½ï¿½ï¿½îµï¿½ë¼â·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ò²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½æ´×ªï¿½ï¿½ï¿½ä·ï¿½ï¿½ï¿½ï¿½ï¿½ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ñ§ï¿½ï¿½ï¿½ä¼ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½æµï¿½ï¿½ï¿½ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ã¹«ê½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ð¡ï¿½æ´×ªï¿½ï¿½ï¿½ï¿½?��í¬ñ§ï¿½ï¿½ï¿½ï¿½ï¸ï¿½û²ï¿½ï¿½ï¿½ï¿½ï¿½êµï¿½é£¬ï¿½ß¹û²ï¿½ï¿½ë¼ï¿½ï¿½ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½æ´ï¿½éµä¼ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ö®ï¿½ï¿½ä¹ï¿½ïµï¿½ï¿½ï¿½ï¿½ê¦ï¿½ï¿½ê¾ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ê½ï¿½æµï¿½ï¿½ï¿½ê¾ï¿½ì¾ß£ï¿½ï¿½ï¿½ô²ï¿½ï¿½ï¿½äµï¿½ï¿½ï¿½ö³ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½èµï¿½ï¿½ï¿½ï¿½ï¿½(����ò»ï¿½ï¿½îª16��)��è»ï¿½ï¿½ï¿½ô²ï¿½ï¿½ï¿½ð¿ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½í¼æ´ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½(í¼ï¿½ï¿½ï¿½ì²ï¿½)�í½ï¿½ï¿½ï¿½ï¿½ï¿½ò»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½å¡£ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ó£¬·ö³éµï¿½ï¿½ï¿½ï¿½ï¿½ô½ï¿½à£¬æ´ï¿½éµï¿½ï¿½ï¿½ï¿½ï¿½í¼ï¿½î¾ï¿½ô½ï¿½ó½ï¿½ï¿½ú³ï¿½ï¿½ï¿½ï¿½å¡£
����(4)���û²ï¿½ï¿½ã³ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
�������ü¸ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½êµï¿½ï¿½ã³ï¿½ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ã¹«ê½ï¿½ï¿½?îªê²ã´?��ñ§ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½û£ï¿½ô²ï¿½ï¿½ï¿½ï¿½í¨ï¿½ï¿½ï¿½ï¿½æ´ï¿½ï¿½ô²ï¿½ï¿½ï¿½ï¿½×ªï¿½ï¿½ï¿½é½ï¿½ï¿½æµï¿½ �塣���������äµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ô²ï¿½ï¿½ï¿½ï¿½äµï¿½ï¿½ï¿½ï¿½ �����������ä¸ï¿½ï¿½ï¿½ô²ï¿½ï¿½ï¿½ï¿½ä¸ï¿½ ����îªï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½úµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ô¸ß£ï¿½ï¿½ï¿½ï¿½ô£ï¿½ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ã¹«ê½ï¿½ç£ï¿½ ��(���飺ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½=�������)����ä¸ï¿½ï¿½ê¾ï¿½ï¿½ ��(���飺v=sh)
����(5)ð¡ï¿½á¡£
����ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½æµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½?����ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½öªï¿½ï¿½ï¿½ï¿½ð©ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
����4����ñ§ï¿½ï¿½1��
������ê¾ï¿½ï¿½1�����⡣���ê£ï¿½ï¿½ï¿½ï¿½ü¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½?ö¸ï¿½ï¿½ò»í¬ñ§ï¿½ï¿½ï¿½ý£ï¿½ï¿½ï¿½ï¿½ï¿½ñ§ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï°ï¿½ï¿½ï¿½ï¡ï¿½ï¿½ï¿½ï¿½å¶©ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ê½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ê²ã´?ó¦×¢ï¿½ï¿½ï¿½ï¿½ð©ï¿½ï¿½ï¿½ï¿½?(��î»í³ò»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½î»)
����0.9��=90���� 2490=2160���������ף�
����5������ï°ï¿½ï¿½ï¿½ï¿½1�⡣
������ñ§ï¿½ï¿½ï¿½ï¿½ï¿½ú¿î±ï¿½ï¿½ï¡ï¿½ö¸ï¿½ï¿½ï¿½ú´ð£¬¼ï¿½ï¿½å¶©ï¿½ï¿½ï¿½ï¿½×·ï¿½ê£ï¿½ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½?
����6����ñ§ï¿½ï¿½ò»ï¿½ï¿½ò»ï¿½ï¿½ô²ï¿½ï¿½ï¿½äµï¿½ï¿½ï¿½ë¾¶ï¿½ï¿½2���ף�����8�ף������������ö¸ï¿½ï¿½ò»ï¿½ë°ï¿½ï¿½ý£ï¿½ï¿½ï¿½ï¿½ï¿½ñ§ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï°ï¿½ï¿½ï¿½ï¡ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ò»ï¿½ï¿½ð¡ï¿½á£ºï¿½ï¿½ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½öªï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½í¸ß¡ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½öªï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ö»öªï¿½ï¿½ï¿½ë¾¶r��í¨ï¿½ï¿½ê²ã´í¾ï¿½ï¿½ï¿½ï¿½ï¿½ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½?���öªï¿½ï¿½d��?öªï¿½ï¿½c��?öªï¿½ï¿½r��d��c����òªï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
����7. ��ñ§ï¿½ï¿½2��
������ê¾ï¿½ï¿½2�����⡣ð¡ï¿½ï¿½ï¿½ï¿½ï¿½û¼ï¿½ï¿½ã·½ï¿½ï¿½ï¿½ï¿½è»ï¿½ï¿½ñ§ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï°ï¿½ï¿½ï¿½ï¡ï¿½ï¿½ï¿½ï¿½å¶©ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ê½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ê²ã´?ó¦×¢ï¿½ï¿½ï¿½ï¿½ð©ï¿½ï¿½ï¿½ï¿½?(��î»í³ò»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½î»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½)
北师大版数学六年级下册2-4页。
1. 通过观察面的旋转的特点,理解圆柱和圆锥的形成与面的旋转之间的关系。
2. 联系生活,在生活中辨认圆柱和圆锥体的物体,并能抽象出几何图形的形状来。
3. 通过观察,初步了解圆柱和圆锥的组成及其特点。
联系生活,在生活中辨认圆柱和圆锥体的物体,并能抽象出几何图形的形状来。
通过观察,初步了解圆柱和圆锥的组成及其特点。
1. 将自行车后轮支架支起,在后轮辐条上系上彩带。转动后轮,观察并思考彩带随车轮转动形成的图形是什么?
请学生想象后回答自己的想法。
2. 观察下图,你发现了什么?
延伸的铁路,雨刮器刮过的车窗,旋转门。
3. 用纸片和小棒做成小旗,快速旋转小棒,观察并想象纸片旋转后所形成的图形,再连一连。
4. 介绍:圆柱、圆锥、球的名称。并请学生根据自己的观察介绍一下这几个立体图形的特点。
小结:我们学过的长方体、正方体都是由平面围成的立体图形,今天我们学习的圆柱、圆锥和球也是立体图形,只是与长方体、正方体不同,围成的图形上可能有曲面。
5. 找一找:请你找出我们学过的立体图形。
1. 圆柱与圆锥分别有什么特点?
2. 认识圆柱和圆锥各部分的名称。
圆柱的上下两个面叫做底面,它们是完全相同的两个圆。
圆柱有一个曲面,叫做侧面。
圆柱两个底面之间的距离叫做高。
圆锥的底面是一个圆。
圆锥的侧面是一个曲面。
从圆锥顶点到底面圆心的距离是圆锥的高。
教师画出平面图进行讲解。并在图上标出各部分的名称。
3. 找一找下面的物体中,哪些部分的形状是圆柱或圆锥?
4. 找一找还有哪些物体的形状是圆柱或圆锥?
5. 下面图形是圆柱或圆锥的在括号里写出图形的名称,并标出底面直径和高。
6. 想一想,转动后会形成怎样的图形?
7. 看图算出箱子的长、宽和高。
北师大版教学六年级《圆柱的体积》
1、结合具体的情境和实践活动,理解圆柱体体积的含义。
2、经历探索圆柱体积计算方法的过程,掌握圆柱体积的计算方法,能正确计算圆柱的体积,并会解决一些简单的实际问题。
3、培养学生初步的空间观念和思维能力;
理解和掌握圆柱的体积计算公式,会求圆柱的体积。
理解圆柱体积计算公式的推导过程。
圆柱体积演示教具。
1、谈话引入
最近我们认识了圆柱和圆锥,还学会了计算圆柱的表面积。现在请看老师的这个圆柱形杯子和这个圆柱比较,谁大?这里所说的大小实际是指它们的什么?(生答)
2、提出问题:什么叫体积?我们学过那些图形的体积?怎么算的?(生答师随之板书)
这节课我们就来学习圆柱的体积。
(一)认识圆柱体积的意义。
圆柱的体积到底是指什么?谁能举例说呢?
(二)圆柱体积的计算公式的推导。
1、我们学过长方体和正方体体积的计算,圆柱体的体积跟什么有关呢?你会有怎样的猜想?(小组内说说)
2、回忆圆面积的推导过程。
3、教具演示。
(1)取圆柱体模型。
(2)将圆柱体切成两半。
(3)分别将两半均分成若干小块。
(4)动手拼成一个近似的长方体。
(三)归纳公式。
(板书:圆柱的体积=底面积高)
用字母表示:(板书:v=sh)
1、这个杯子的底面半径为6厘米,高为16厘米,它的体积是多少?
审题。提问:你能独立完成这题吗?指名一同学板演,其余学生做在练习本上。
现在这个杯子装了2/3的水,装了多少水呢?
2、完成试一试
3、跳一跳:统一直柱体的体积的计算方法。
这节课学习了什么内容?圆柱的体积怎样计算,这个公式是怎样得到的?这个公式适合哪些图形?他们有什么共同特点?
练一练1-5题。
����
������ê¦ï¿½ï¿½ï¿½ð¡ñ§ï¿½ï¿½ñ§ï¿½ï¿½ï¿½ê¼¶ï¿½â²ï¿½ï¿½ü¸ï¿½ï°ï¿½ðµï¿½78-79ò³ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
����
����öªê¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½:
����1����ò»ï¿½ï¿½ï¿½ï¿½ê¶í¼ï¿½îµï¿½æ½ï¿½æ£ï¿½ï¿½ï¿½×ªï¿½ï¿½ï¿½ï¿½ô³æ¡ï¿½
����2����è·ï¿½ï¿½ï¿½ï¿½ô³ï¿½í¼ï¿½îµä¶ô³ï¿½ï¿½á£¬ï¿½ï¿½ï¿½ú·ï¿½ï¿½ï¿½ö½ï¿½ï»ï¿½ï¿½ï¿½ò»ï¿½ï¿½í¼ï¿½îµï¿½ï¿½ï¿½ô³ï¿½í¼ï¿½î£ï¿½ï¿½ü½ï¿½ï¿½òµ¥µï¿½í¼ï¿½ï¿½æ½ï¿½æ»ï¿½ï¿½ï¿½×ª90�㡣
����
����������ñ§ï¿½ï¿½ï¿½ï¿½æ½ï¿½ï¿½í¼ï¿½îµï¿½ï¿½ï¿½ô³ï¿½ï¿½ô£ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ð©í¼ï¿½îµï¿½ï¿½ï¿½ê¶ï¿½ï¿½
�����������æ½ï¿½æ£ï¿½ï¿½ï¿½×ªï¿½ï¿½ï¿½ï¿½ô³ï¿½ï¿½ú·ï¿½ï¿½ï¿½ö½ï¿½ï¿½ï¿½ï¿½ï¿½í¼ï¿½ï¿½ï¿½ï¿½
�������ì¬ï¿½ï¿½ï¿½ï¿½ï¿½öµï¿½û£ï¿½
�����ú¹û²ì¡¢ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½í¼ï¿½ï¿½ï¿½è»î¶¯ï¿½ð£ï¿½ï¿½ï¿½õ¹ï¿½õ¼ï¿½ï¿½ï¿½î¡£
����
������ò»ï¿½ï¿½ï¿½ï¿½ï¿½õ¶ô³æ¡ï¿½æ½ï¿½æ¡ï¿½ï¿½ï¿½×ªï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
����
�����ûºï¿½ï¿½ï¿½ï¿½ï¿½æ½ï¿½æ¡ï¿½ï¿½ï¿½×ªï¿½ï¿½ô³æµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½í¼ï¿½îµä±ä»»ï¿½ï¿½ï¿½ï¿½ò»ï¿½ï¿½ï¿½ï¿½õ¹ñ§ï¿½ï¿½ï¿½õ¼ï¿½ï¿½ï¿½î¡£
����
����ò»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½é¾³ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
����ê¦ï¿½ï¿½í¬ñ§ï¿½ç£ï¿½ï¿½ï¿½ï¿½ï¿½ä©ï¿½ï¿½ï¿½ç°ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ö°ö¡ï¿½ï¿½ï¿½ï¿½ï¿½ò»ï¿½ï¿½è¥ï¿½ï¿½ò»ï¿½ï¿½ï¿½ø·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ò»ï¿½ï¿½è¥ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
�������î¼ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ö³ï¿½ï¿½é¾°ï¿½ï¿½ä¦ï¿½ï¿½ï¿½ö¡ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½×ªä¾ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ý¡ï¿½ï¿½æ³ï¿½ï¿½ï¿½ð¡ï¿½ð³µ¡ï¿½ï¿½ù»ï¿½ï¿½ï¿½
����ê¦ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ô°ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä¿ï¿½ï¿½ï¿½ë¶ï¿½ï¿½ä»¯ï¿½ï¿½í¬ï¿½ð£¿£ï¿½ñ§ï¿½ï¿½ëµï¿½ï¿½ï¿½à·½ï¿½ï¿½ï¿½ï¿½
������1��������ô°ï¿½ï¿½ï¿½ñ»¬»ï¿½ï¿½ý¡ï¿½ï¿½æ³ï¿½ï¿½ï¿½ð¡ï¿½ð³µ¡ï¿½ï¿½ù»ï¿½ï¿½ï¿½ð©ï¿½ï¿½ï¿½å¶¼ï¿½ï¿½ï¿½ï¿½ö±ï¿½ï¿½ï¿½æ¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½æ½ï¿½æ¡ï¿½ï¿½ï¿½2��ä¦ï¿½ï¿½ï¿½ö¡ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½×ªä¾ï¿½ï¿½ï¿½ï¿½ð©ï¿½ï¿½ï¿½å¶¼ï¿½ï¿½ï¿½ï¿½ò»ï¿½ï¿½ï¿½ï¿½ï¿½ò»ï¿½ï¿½ï¿½ï¿½ï¿½æ¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½×ªï¿½ï¿½
����ê¦ï¿½ï¿½æ½ï¿½æºï¿½ï¿½ï¿½×ªï¿½ï¿½ï¿½ï¿½ï¿½ç³ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ë¶ï¿½ï¿½ï¿½ê½ï¿½ï¿½ï¿½ï¿½ñ§ï¿½ï¿½ï¿½ï¿½ï¿½ç³ï¿½îªï¿½ä»»ï¿½ï¿½ê½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ö·ï¿½ê½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ö·ï¿½ê½ï¿½ï¿½ï¿½ô³ï¿½îªï¿½ä»»ï¿½ø£ï¿½
����������ô³æ¡ï¿½
����ê¦ï¿½ï¿½ï¿½ï¿½ï¿½ç½ï¿½ï¿½ï¿½ï¿½ò»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï°í¼ï¿½ï¿½ï¿½ï¿½ä»»ï¿½ï¿½öªê¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½â£©
北师大版小学数学六年级下册总复习中第78-79页的内容
知识与能力:
1、进一步认识图形的平移,旋转与轴对称。
2、能确定轴对称图形的对称轴,能在方格纸上画出一个图形的轴对称图形,能将简单的图形平移或旋转90°。
整理已学过的平面图形的轴对称性,加深对这些图形的认识。
灵活运用平移,旋转和轴对称在方格纸上设计图案。
情感态度与价值观:
在观察、操作、想象、设计图案等活动中,发展空间观念。
进一步掌握对称、平移、旋转的特征。
综合运用平移、旋转与对称的特征进行图形的变换,进一步发展学生空间观念。
一、创设情境,引入课题
师:同学们,上周末咱们班的李坤和王明随爸爸、妈妈一起去了一个地方。想跟他们一起去看看吗?
(课件出现游乐场情景:摩天轮、穿梭机、旋转木马、滑滑梯、推车、小火车、速滑)
师:游乐园里各种游乐项目的运动变化相同吗?(学生说分类方法)
生1:在游乐园里像滑滑梯、推车、小火车、速滑这些物体都是沿直线移动,这样的现象叫做平移。生2:摩天轮、穿梭机、旋转木马这些物体都绕着一个点或一个轴移动,这样的现象叫做旋转。
师:平移和旋转是我们常见的物体的运动方式,数学上我们称为变换方式,除了这两种方式,还有哪种方式可以称为变换呢?
生:轴对称。
师:我们今天就一起来复习图形与变换的知识。(板书课题)
����
������ê¦ï¿½ï¿½ï¿½ï¿½ñ§ï¿½ï¿½ï¿½ê¼¶ï¿½ï¿½ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
����
����1����ï¾ï¿½ï¿½ï¿½ï¿½ï¿½é¾³ï¿½ï¿½êµï¿½ï¿½ï¿½î¶¯ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½äºï¿½ï¿½å¡£
����2������ì½ï¿½ï¿½ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ã·½ï¿½ï¿½ï¿½ä¹ï¿½ï¿½ì£ï¿½ï¿½ï¿½ï¿½ï¿½ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä¼ï¿½ï¿½ã·½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½è·ï¿½ï¿½ï¿½ï¿½ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ò»ð©ï¿½òµ¥µï¿½êµï¿½ï¿½ï¿½ï¿½ï¿½â¡£
����3������ñ§ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä¿õ¼ï¿½ï¿½ï¿½ï¿½ï¿½ë¼î¬ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
����
�������������ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ã¹«ê½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
����
��������ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ã¹«ê½ï¿½ï¿½ï¿½æµï¿½ï¿½ï¿½ï¿½ì¡ï¿½
����
����ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ê¾ï¿½ì¾ß¡ï¿½
����
����
����1��ì¸ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
�������������ê¶ï¿½ï¿½ô²ï¿½ï¿½ï¿½ï¿½ô²×¶ï¿½ï¿½ï¿½ï¿½ñ§ï¿½ï¿½ï¿½ë¼ï¿½ï¿½ï¿½ô²ï¿½ï¿½ï¿½ä±ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ë¿´ï¿½ï¿½ê¦ï¿½ï¿½ï¿½ï¿½ï¿½ô²ï¿½ï¿½ï¿½î±ï¿½ï¿½óºï¿½ï¿½ï¿½ï¿½ô²ï¿½ï¿½ï¿½è½ï£ï¿½ë��������ëµï¿½ä´ï¿½ð¡êµï¿½ï¿½ï¿½ï¿½ö¸ï¿½ï¿½ï¿½çµï¿½ê²ã´ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
����2��������⣺ê²ã´ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ñ§ï¿½ï¿½ï¿½ï¿½ð©í¼ï¿½îµï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ã´ï¿½ï¿½ä£ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ê¦ï¿½ï¿½ö®ï¿½ï¿½ï¿½é£©
������ú¿ï¿½ï¿½ï¿½ï¿½ç¾ï¿½ï¿½ï¿½ñ§ï°ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
����
������ò»ï¿½ï¿½ï¿½ï¿½ê¶ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½å¡£
����ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ö¸ê²ã´ï¿½ï¿½ë�ü¾ï¿½ï¿½ï¿½ëµï¿½ø£ï¿½
����������ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä¼ï¿½ï¿½ã¹«ê½ï¿½ï¿½ï¿½æµï¿½ï¿½ï¿½
����1������ñ§ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä¼ï¿½ï¿½ã£¬ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ê²ã´ï¿½ð¹ï¿½ï¿½ø£ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä²ï¿½ï¿½ë£¿ï¿½ï¿½ð¡ï¿½ï¿½ï¿½ï¿½ëµëµï¿½ï¿½
����2������ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½æµï¿½ï¿½ï¿½ï¿½ì¡ï¿½
����3���ì¾ï¿½ï¿½ï¿½ê¾ï¿½ï¿½
������1��è¡ô²ï¿½ï¿½ï¿½ï¿½ä£ï¿½í¡ï¿½
������2����ô²ï¿½ï¿½ï¿½ï¿½ï¿½ð³ï¿½ï¿½ï¿½ï¿½ë¡£
������3���ö±ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ö³ï¿½ï¿½ï¿½ï¿½ï¿½ð¡ï¿½é¡£
������4������æ´ï¿½ï¿½ò»ï¿½ï¿½ï¿½ï¿½ï¿½æµä³ï¿½ï¿½ï¿½ï¿½å¡£
�������������é¹ï¿½ê½ï¿½ï¿½
���������飺ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½=������ߣ�
��������ä¸ï¿½ï¿½ê¾ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½é£ºv=sh��
����
����1��������óµäµï¿½ï¿½ï¿½ë¾¶îª6���ף���îª16���ף���������ç¶ï¿½ï¿½ù£ï¿½
�������⡣���ê£ï¿½ï¿½ï¿½ï¿½ü¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ö¸ï¿½ï¿½ò»í¬ñ§ï¿½ï¿½ï¿½ý£ï¿½ï¿½ï¿½ï¿½ï¿½ñ§ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï°ï¿½ï¿½ï¿½ï¡ï¿½
���������������װ��2/3��ë®ï¿½ï¿½×°ï¿½ë¶ï¿½ï¿½ï¿½ë®ï¿½ø£ï¿½
����2�������ò»ï¿½ï¿½
����3����ò»ï¿½ï¿½ï¿½ï¿½í³ò»ö±ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ä¼ï¿½ï¿½ã·½ï¿½ï¿½ï¿½ï¿½
����
������ú¿ï¿½ñ§ï°ï¿½ï¿½ê²ã´ï¿½ï¿½ï¿½ý£ï¿½ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ã£¬ï¿½ï¿½ï¿½ï¿½ï¿½ê½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ãµï¿½ï¿½ä£ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ê½ï¿½êºï¿½ï¿½ï¿½ð©í¼ï¿½î£ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ê²ã´ï¿½ï¿½í¬ï¿½øµã£¿
����
������ò»ï¿½ï¿½1-5�⡣
����
������ê¦ï¿½ï¿½ï¿½ï¿½ï¿½ñ§ï¿½ï¿½ï¿½ê¼¶ï¿½â²ï¿½2-4ò³ï¿½ï¿½
����
����1. í¨ï¿½ï¿½ï¿½û²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½×ªï¿½ï¿½ï¿½øµã£¬ï¿½ï¿½ï¿½ï¿½ô²ï¿½ï¿½ï¿½ï¿½ô²×¶ï¿½ï¿½ï¿½î³ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½×ªö®ï¿½ï¿½ä¹ï¿½ïµï¿½ï¿½
����2. ��ïµï¿½ï¿½ï¿½î£¬ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ð±ï¿½ï¿½ï¿½ô²ï¿½ï¿½ï¿½ï¿½ô²×¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½å£¬ï¿½ï¿½ï¿½ü³ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½í¼ï¿½îµï¿½ï¿½ï¿½×´ï¿½ï¿½ï¿½ï¿½
����3. í¨ï¿½ï¿½ï¿½û²ì£¬ï¿½ï¿½ï¿½ï¿½ï¿½ë½ï¿½ô²ï¿½ï¿½ï¿½ï¿½ô²×¶ï¿½ï¿½ï¿½ï¿½é¼ï¿½ï¿½ï¿½ï¿½øµã¡£
����
������ïµï¿½ï¿½ï¿½î£¬ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ð±ï¿½ï¿½ï¿½ô²ï¿½ï¿½ï¿½ï¿½ô²×¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½å£¬ï¿½ï¿½ï¿½ü³ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½í¼ï¿½îµï¿½ï¿½ï¿½×´ï¿½ï¿½ï¿½ï¿½
����
����í¨ï¿½ï¿½ï¿½û²ì£¬ï¿½ï¿½ï¿½ï¿½ï¿½ë½ï¿½ô²ï¿½ï¿½ï¿½ï¿½ô²×¶ï¿½ï¿½ï¿½ï¿½é¼ï¿½ï¿½ï¿½ï¿½øµã¡£
����
����
����1. �����ð³ï¿½ï¿½ï¿½ï¿½ï¿½ö§ï¿½ï¿½ö§ï¿½ï¿½ï¿½úºï¿½ï¿½ö·ï¿½ï¿½ï¿½ï¿½ï¿½ïµï¿½ï²ê´ï¿½ï¿½ï¿½×ªï¿½ï¿½ï¿½ï¿½ï¿½ö£ï¿½ï¿½û²ì²¢ë¼ï¿½ï¿½ï¿½ê´ï¿½ï¿½æ³µï¿½ï¿½×ªï¿½ï¿½ï¿½î³éµï¿½í¼ï¿½ï¿½ï¿½ï¿½ê²ã´ï¿½ï¿½
������ñ§ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ø´ï¿½ï¿½ô¼ï¿½ï¿½ï¿½ï¿½ë·¨ï¿½ï¿½
����2. �û²ï¿½ï¿½ï¿½í¼ï¿½ï¿½ï¿½ã·¢ï¿½ï¿½ï¿½ï¿½ê²ã´ï¿½ï¿½
�����������â·ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½î¹ï¿½ï¿½ä³ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½×ªï¿½å¡ï¿½
����3. ��ö½æ¬ï¿½ï¿½ð¡ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ð¡ï¿½ì£¬ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½×ªð¡ï¿½ï¿½ï¿½ï¿½ï¿½û²ì²¢ï¿½ï¿½ï¿½ï¿½ö½æ¬ï¿½ï¿½×ªï¿½ï¿½ï¿½ï¿½ï¿½î³éµï¿½í¼ï¿½î£ï¿½ï¿½ï¿½ï¿½ï¿½ò»ï¿½ï¿½ï¿½ï¿½
����4. ���ü£ï¿½ô²ï¿½ï¿½ï¿½ï¿½ô²×¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½æ¡ï¿½ï¿½ï¿½ï¿½ï¿½ñ§ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ô¼ï¿½ï¿½ä¹û²ï¿½ï¿½ï¿½ï¿½ò»ï¿½ï¿½ï¿½â¼¸ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½í¼ï¿½îµï¿½ï¿½øµã¡£
����ð¡ï¿½á£ºï¿½ï¿½ï¿½ï¿½ñ§ï¿½ï¿½ï¿½ä³ï¿½ï¿½ï¿½ï¿½å¡¢ï¿½ï¿½ï¿½ï¿½ï¿½å¶¼ï¿½ï¿½ï¿½ï¿½æ½ï¿½ï¿½î§ï¿½éµï¿½ï¿½ï¿½ï¿½ï¿½í¼ï¿½î£ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ñ§ï°ï¿½ï¿½ô²ï¿½ï¿½ï¿½ï¿½ô²×¶ï¿½ï¿½ï¿½ï¿½ò²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½í¼ï¿½î£ï¿½ö»ï¿½ï¿½ï¿½ë³¤ï¿½ï¿½ï¿½å¡¢ï¿½ï¿½ï¿½ï¿½ï¿½å²»í¬ï¿½ï¿½î§ï¿½éµï¿½í¼ï¿½ï¿½ï¿½ï¿ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½æ¡£
����5. ��ò»ï¿½ò£ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ò³ï¿½ï¿½ï¿½ï¿½ï¿½ñ§ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½í¼ï¿½î¡ï¿½
����
����1. ô²ï¿½ï¿½ï¿½ï¿½ô²×¶ï¿½ö±ï¿½ï¿½ï¿½ê²ã´ï¿½øµã£¿
����2. ��ê¶ô²ï¿½ï¿½ï¿½ï¿½ô²×¶ï¿½ï¿½ï¿½ï¿½ï¿½öµï¿½ï¿½ï¿½ï¿½æ¡ï¿½
����ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½æ£¬ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½è«ï¿½ï¿½í¬ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ô²ï¿½ï¿½
����ô²ï¿½ï¿½ï¿½ï¿½ò»ï¿½ï¿½ï¿½ï¿½ï¿½æ£¬ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½æ¡£
����ô²ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ö®ï¿½ï¿½ä¾ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ß¡ï¿½
����ô²×¶ï¿½äµï¿½ï¿½ï¿½ï¿½ï¿½ò»ï¿½ï¿½ô²ï¿½ï¿½
����ô²×¶ï¿½ä²ï¿½ï¿½ï¿½ï¿½ï¿½ò»ï¿½ï¿½ï¿½ï¿½ï¿½æ¡£
������ô²×¶ï¿½ï¿½ï¿½ãµ½ï¿½ï¿½ï¿½ï¿½ô²ï¿½äµä¾ï¿½ï¿½ï¿½ï¿½ï¿½ô²×¶ï¿½ä¸ß¡ï¿½
������ê¦ï¿½ï¿½ï¿½ï¿½æ½ï¿½ï¿½í¼ï¿½ï¿½ï¿½ð½ï¿½ï¿½â¡£ï¿½ï¿½ï¿½ï¿½í¼ï¿½ï±ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½öµï¿½ï¿½ï¿½ï¿½æ¡ï¿½
����3. ��ò»ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ð£ï¿½ï¿½ï¿½ð©ï¿½ï¿½ï¿½öµï¿½ï¿½ï¿½×´ï¿½ï¿½ô²ï¿½ï¿½ï¿½ï¿½ô²×¶ï¿½ï¿½
����4. ��ò»ï¿½ò»ï¿½ï¿½ï¿½ï¿½ï¿½ð©ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½×´ï¿½ï¿½ô²ï¿½ï¿½ï¿½ï¿½ô²×¶ï¿½ï¿½
����5. ����í¼ï¿½ï¿½ï¿½ï¿½ô²ï¿½ï¿½ï¿½ï¿½ô²×¶ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ð´ï¿½ï¿½í¼ï¿½îµï¿½ï¿½ï¿½ï¿½æ£ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ö±ï¿½ï¿½ï¿½í¸ß¡ï¿½
����6. ��ò»ï¿½ë£¬×ªï¿½ï¿½ï¿½ï¿½ï¿½ï¿½î³ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½í¼ï¿½î£ï¿½
����7. ��í¼ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½óµä³ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½í¸ß¡ï¿½
北师大版六年级数学下册教学教案(28篇)
文件夹