恐龙无处不有.pptx

1、6500万年前，在地球上生活了1.6亿年的恐龙突然灭绝了，这成了生物史上最大的谜。不同地域恐龙化石的发现意味着什么？导致恐龙灭绝的原因是什么？我们一起来学习美国著名科普作家和科学幻想小说家阿西莫夫的科普短文两篇，看看他是怎样为我们揭开谜底的。,6 阿西莫夫短文两篇,R八年级语文下册,1.了解文中揭示的恐龙灭绝的原因，把握作者在两篇短文中阐释的观点。(重点) 2.理清说明顺序，分析说明方法及其作用，体会文章严谨的论证思路。(难点) 3.激发对科学世界的兴趣，培养主动探究科学的精神。(重点),学习目标,阿西莫夫(19201992)，美国科幻、科普作家。曾获代表科幻世界最高荣誉的雨果奖和星云终身成就

2、“大师奖”，是公认的当今美国科幻小说界的泰斗。代表作有机器人系列、基地系列、钢窟系列等。,作者名片,6500万年前，在地球上生活了1.6亿年的恐龙突然灭绝了，这成为了地球生命史上的一大悬案。20世纪70年代以来，有关恐龙灭绝的假说纷纷出现，展开了一场大争论。美国科普作家阿西莫夫从不同领域的科学发现中受到启发，追寻恐龙灭绝原因，写成此文。,背景链接,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路

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5、角度向下飞。 天衣无缝：比喻事物没有一点破绽。 褶皱：由于地壳运动，岩层受力而形成的波状弯曲构造形式。 劫难：灾难，灾祸。 致密：细致精密。,膨胀：由于温度升高或其他因素，物体的长度增加或体积增长。 熔化：固体加热到一定温度变为液体。 追溯：逆流而上，向江河发源处走，比喻探索事物的由来。,恐龙无处不在,1.自由朗读课文，了解课文内容。 2.划分文章层次，理清作者的写作思路。,整体感知,文章结构：,第一部分（1）：不同科学领域是紧密相连的。,第二部分（214）：举例说明南极洲恐龙化石的发现，证明大陆漂移假说，印证主旨。,第三部分（15）：总结南极洲恐龙化石的发现，为大陆漂移假说提供新的证据，结束

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8、成才路,状元成才路,一、快速读课文，回答问题：,本文依据_的事实，证明了_假说。,在南极发现恐龙化石,大陆漂移,课文说明的对象涉及两个学科，即：_ _。,生物学,从中我们明白一个什么道理？,课文解读,（恐龙）、地质学（板块理论）,想一想：作者把这两句放在开头有什么作用？,开头突发议论，这两句议论是全篇行文的逻辑基础。用“紧密相连”“影响”等词语揭示事物之间的联系。,不同科学领域之间是紧密相连的。在一个科学领域的发现肯定会对其他领域产生影响。,道理：,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状

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11、也许会缓慢地向另一板块下面俯冲。,2.“板块构造”理论为地质界的哪些问题提供了答案？,火山、地震、岛屿链、海洋深渊等问题。,二、默读课文，探究问题：,3.为什么要写恐龙化石？在南极发现恐龙化石说明了什么问题？,写恐龙化石是为了利用恐龙化石在南极的发现说明“恐龙无处不在”，再由“恐龙无处不在”给大陆漂移假说提供有力证据，进而说明大陆在漂移而不是恐龙自己在迁移。,4.“泛大陆”是怎样形成的？,地壳是由一些紧密拼合在一起但又缓慢运动的大板块构成的，板块背上驮着许多大陆，板块运动时大陆也随之一起运动。每隔一段时期，板块会将所有的大陆汇聚在一起，地球此时仅由一个主要陆地构成，这就是“泛大陆”。,状元成才

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14、“大陆漂移”学说推断思路：,南极发现恐龙化石。,恐龙并不适应南极气候。,大陆在迁移而不是恐龙在迁移。,提出大陆板块构造理论。,“泛大陆”形成时，所有陆地都处在热带和温带环境中，适合恐龙生活。,由此推断“泛大陆”分裂成四部分。,每一块大陆都携带着自己的恐龙而去。,打比方,四、精读课文，理解方法。,本文运用了哪些说明方法？请举例说明。,运用打比方的方法，使得语言既生动又明白如话，例如：“位于南极中心部位的南极洲是全球的大冰箱”一句，形象地说明了南极洲寒冷的程度和南极洲在地球中的重要地位。,在文章中，作者举了许多例子来说明自己的观点。例如，为了证明不仅南极大陆有恐龙化石这一说法，列举“在地球的其他大

15、陆上也都发现有恐龙化石”，“说明恐龙确实遍布于世界各地”；举“火山、地震、岛屿链、海洋深渊等等”的例子，说明“板块构造”理论为地质界几乎所有的问题提供了答案，解开了许多地质之谜。,举例子,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元

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