《摆的研究》教学设计
云和县城西小学 蓝陶凌云
【教学目标】
1.科学概念:摆的摆动快慢与摆绳的长度有关,同一个摆,摆绳越长摆动越慢,摆绳越短摆动越快。
2.过程与方法:能制作一个15s摆动15次的摆,并在这个过程中体验影响摆摆动快慢的因素。
3.情感、态度、价值观:意识到感觉是会出错的,深刻理解重复精确实验的价值 ;感受探究单摆的快乐。
【教学重点】
制作一个15s摆动15次的摆。
【教学难点】
通过分析制作摆的过程中获得的数据得出影响摆动快慢的因素。
【教学准备】
学生材料:计时器、单摆装置一个(铁架台、挂有磁铁的棉线、劈开的筷子)、磁铁一块、记录单。
教师材料:学生材料一套、不同的单摆两个、铁架台两个、量角器、课件。
【教学过程】
mso-hansi-font-family:"Times New="New" Roman"">一、引入
1mso-hansi-font-family:"Times New="New" Roman"">.平常你们是怎么计算时间的? Amso-hansi-font-family:"Times New="New" Roman"">:用手表、看电视、广播、电脑
2mso-hansi-font-family:"Times New="New" Roman"">.今天老师给大家介绍一种计时工具—机械摆钟,这是一种古老的计时工具,先来了解下机械摆钟(看视频),机械摆钟每分钟能摆动60"Times New="New" Roman"">次,
3.mso-hansi-font-family:"Times New="New" Roman"">它的主要结构是摆,今天我们来学习摆(板书:摆的研究)
二、实验前的活动
1mso-hansi-font-family:"Times New="New" Roman"">.首先来认识下摆的结构,一根绳子挂上重物就成了最简单的单摆(这个重物是一块磁铁),将单摆夹在劈开的筷子上,绳子的一端从劈开的筷子中再绕一下(知道为什么吗?),挂的重物就是摆锤,从悬挂点开始到重物,就是摆绳。(ppt"Times New="New" Roman"">同步)
2mso-hansi-font-family:"Times New="New" Roman"">.用手指钩住摆锤,拉开一定的幅度,这个幅度称为摆幅,再轻轻放开,摆就会来回摆动。
3.mso-hansi-font-family:"Times New="New" Roman"">刚才我们说机械摆钟每分钟摆动60次,那怎么样算一次呢?(学生先回答):从最高点摆过去再摆回来,算一次。那这个摆能摆动几次呢("Times New="New" Roman"">你觉得能测几次?Amso-hansi-font-family:"Times New="New" Roman"">:(每个人都有自己的猜测,那我们不如试一下吧?)(mso-hansi-font-family:"Times New="New" Roman";color:red">可是怎么测呢?mso-hansi-font-family:"Times New="New" Roman"">要不要规定时间?)"Times New="New" Roman"">(要),我们也可以测1mso-hansi-font-family:"Times New="New" Roman"">分钟,但1分钟稍微有点长,时间关系,我们就测15s"Times New="New" Roman"">内摆动的次数。那我们先把计时器调到15s,我来计时,你们来数。(重复三次) mso-hansi-font-family:"Times New="New" Roman";color:red">(增加与学生的互动,来调动学生的积极性和学习兴趣,而不是一个人在讲)
4mso-hansi-font-family:"Times New="New" Roman"">.看来你们已经学会记录次数了。机械摆钟1"Times New="New" Roman"">分钟摆动60mso-hansi-font-family:"Times New="New" Roman"">次,15s就是15"Times New="New" Roman"">次,我做的摆15smso-hansi-font-family:"Times New="New" Roman"">才摆动X次,你们能不能来制作一个15s"Times New="New" Roman"">摆动15mso-hansi-font-family:"Times New="New" Roman"">次的摆呢?
Qmso-hansi-font-family:"Times New="New" Roman"">:你准备怎么做?(改变摆锤、摆绳、摆幅) 理由是什么?
5mso-hansi-font-family:"Times New="New" Roman"">.除了这些材料老师还给大家准备了一块磁铁,可以作为摆锤,计时器已经会使用了,还有些注意点要提醒大家。
(1"Times New="New" Roman"">)摆绳要拉直,放开摆锤轻轻放下,不要推。
(2"Times New="New" Roman"">)摆幅不要太大,如果碰到其他物体则需要重新做。
(3"Times New="New" Roman";color:red">)尽量将摆锤放正。分工明确,计时和计数同时开始。
(4"Times New="New" Roman"">)每次只改变一个因素(一个因素一个因素的改变),记录你的方法,再测试15s内摆动的次数,重复三次。计时器重新按开始,又会计时15s"Times New="New" Roman"">。(解释记录单,第一次制作不用写改变的方法)
(5"Times New="New" Roman"">)实验完成后请思考3mso-hansi-font-family:"Times New="New" Roman"">个问题:
A. "Times New="New" Roman"">你是如何调整你的摆的?结果(摆动次数)如何?
B.摆的快慢与什么无关?与什么有关?从哪几组数据可以说明?
C.摆动过快或过慢时该如何调整?
(6"Times New="New" Roman"">)听到音乐,停止实验,将摆放在一边。
6mso-hansi-font-family:"Times New="New" Roman"">.下面开始实验。(25min)
三、汇报
1mso-hansi-font-family:"Times New="New" Roman"">.(1)汇报:你可以按照这样的步骤来汇报,最开始制作的摆摆动的次数,接着如何改变,结果怎么样?(讲解自己的实验过程),说明什么?最后你发现摆的快慢与什么无关?与什么有关?
(2"Times New="New" Roman"">)其他同学有什么疑问?
2mso-hansi-font-family:"Times New="New" Roman"">.可能出现的数据问题
(1"Times New="New" Roman"">)重复的三次数据不一样。追问:(你是怎么做的?)你觉得原因是什么?
(2"Times New="New" Roman"">)改变了摆锤或者摆幅,摆动次数发生改变?追问:(你是怎么做的?)你觉得原因是什么?当场重新再做一遍(拿着他们组的摆)。
3mso-hansi-font-family:"Times New="New" Roman"">.最后得出结论:摆动快慢与摆绳长度有关,摆绳长度越长摆动越慢,摆绳长度越短摆动越快。与摆锤重量和摆幅大小无关。
四、延伸
1mso-hansi-font-family:"Times New="New" Roman"">.老师这里有两个摆绳同样长的摆,但摆锤长度不同,它们摆动快慢如何?
2mso-hansi-font-family:"Times New="New" Roman"">.我们来试一下,测试15s内摆动的次数,左边两组默数长的,右边两组默数短的(同时计时)。
结果:摆锤短的摆动次数快
3mso-hansi-font-family:"Times New="New" Roman"">.为什么摆绳长度相同,摆动次数还是不同呢?是结论有错吗?这个问题希望同学们下课后好好的思考。
【板书设计】
mso-hansi-font-family:"Times New="New" Roman"">摆的研究
"Times New="New" Roman"">摆绳越长摆动越慢,摆绳越短摆动越快
摆的研究实验记录单
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方法
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15s摆动次数
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思考
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第一次
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第二次
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第三次
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1.你是如何调整你的摆的?结果(摆动次数)如何?
2.摆的快慢与什么无关?与什么有关?从哪几组数据可以说明?
3.摆动过快或过慢时该如何调整?
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