“生活中的化學知識”雙語教學課案例

葉燕紅

文章編號：1005－6629(2009)03－0050－03中圖分類號：G633.8文獻標識碼：B

1教學目標

讓學生掌握9個化學術語：acidic basic neutral strong acid-weak base salt weak acid-strong base salt fire extinguisher chlorine alcohol solid-state.

培養學生用化學知識解決實際問題的能力（泡沫滅火器的制取原理、洗潔劑混用的危害、固體酒精的制法）。

讓學生體會化學知識的重要性，感受學以致用的樂趣。

2 教學方法

先與學生討論長大后的理想，引出大家都想為社會做出貢獻的思想。那現在作為一名學生，我們也可以用我們所學來解決一些生活實際問題，進而引出本節課的主題：chemistry knowledge in daily life。接著通過化學知識在生活中的三個常見應用事例（泡沫滅火器的制取原理、洗潔劑混用的危害、固體酒精的制法）,由學生表演、實驗、分析、討論得出學習知識的重要性，最后教師作小結，希望學生們能學有所成，實現自己的夢想，與開頭呼應。

3 教學過程

[第一部分 導入]

[先與學生討論長大以后的理想，進而引到現在作為一名學生，我們可以用我們所學來解決一些生活實際問題，進而引到本節課的主題。]

Teacher: What's your dream? What kind of jobs would you like to do in the future?

Student1: I want to be a journalist.

Student2: I want to be an engineer.

Stndent3: I want to be a teacher， too.

Teacher: Good，in a word , we all want to make great contributions to our society. As a student, we can also use what we've learnt to solve some problems. Today, Let's enjoy three projects. Please try your best to find out the reasons for the three phenomena. OK, let's begin.

[第二部分 表演、實驗、討論、分析]

[討論了化學在生活中的三個應用：泡沫滅火器的制法、慎用洗滌劑以及固體酒精的制法。主要采用的教學方式是由學生表演、學生實驗為主，教師在適當的時候補充。]

[Project 1]

[旁白]: I have two friends, one is aluminum sulfate ,the other is sodium bicarbonate.

Student 1： Hello, everyone, I am aluminum sulfate, please read after me ,can you say something about my properties?

Student 2： Hello, everyone, I am sodium bicarbonate, please read after me ,can you say something about my properties?

Teacher: I will give you some words and expressions to help you.

acidic

basic

neutral

strong acid-weak base salt

weak acid-strong base salt

hydrolyze

[旁白]: One day , when they met together, what will it happen?

Student 1 and Student 2:表演反應的情景。（學生1和學生2打斗過后，彼此互換了衣服，學生1的帽子飛起來了，學生2躺倒在地。打斗：表示在劇烈地反應；互換了衣服：表示反應后有新物質生成；帽子飛起：表示生成了氣體；倒在地上：表示生成了沉淀）。

教室里掌聲如雷。

Teacher: Who can write down the reaction equation on the blackboard?

[Experiment]：請兩位學生上來做實驗。裝置如圖所示。

Teacher: You see, we can put out fire easily in this way. According to this theory, we can make out “fire extinguisher”.

[教師展示實物并提問]：There are two buckets in fire extinguisher, the inside one is made of plastic, the outside one is made of iron. How to put aluminum sulfate and sodium bicarbonate? When we use it, what should we pay attention to?

Students：We should put aluminum sulfate into the bucket which made of plastic and put sodium bicarbonate into the bucket which made of iron. When we use it, we should turn it upside down.

[Project 2]

[旁白]：Mary is a very busy woman , she works in the office from day to night. Sometimes she even works on holidays. So there is little time for her to do some cleaning. Today is a special day ,she needn't go to work. She wants to clean the house. First , she chooses to clean the closestool.

[表演]:瑪麗清洗馬桶。（她先倒了些“潔廁凈”，邊用刷子刷，邊哼著“洗唰唰”的歌，洗了一會，看看效果不怎么好，她把家里其他的洗滌劑都找了出來，她把每種洗滌劑都倒進一點，又刷了一遍，正當她要站起來時，一陣頭暈，她昏倒在地。另兩位學生把她抬出教室后，進來一位“醫生”，手舉一牌，上面寫著：氯氣中毒。）

Teacher: Do you find out anything wrong? What does it happen? Why does Mary faint?

[學生討論]

[幻燈片顯示]：在我們日常生活的清潔劑中，洗潔精和廚房消毒劑是含次氯酸的氯烴化合物，潔廁凈和浴池清潔劑則是酸性洗滌劑，當兩者混合時，容易發生化學反應產生氯氣。氯氣比空氣重，易積存在衛生間的底部。

Teacher: Mary takes in a large amount of chlorine , so she faints. From now on , please tell your mother not to put substance cleaning the toilet and substance cleaning the bowl together. It is dangerous.

[Project 3]

[猜謎] It's a puzzle. I will give you three pieces of information. Try your best to guess what it is as quickly as you can.

It can be found everywhere, such as in the hospital ,in the restaurant and so on.

It exits in a liquid form. It can be lit.

If you drink too much especially before driving , you will be faind by the policeman.

What is it? Who can write down this word on the blackboard?

Student 1: alcohol.

Teacher: We know, in normal temperature, alcohol is a liquid, but sometimeswe can see some solid-state alcohol. What is it? How to make it?

Students: increase the pressure、low the temperature.

[幻燈片顯示]：固體酒精的制法（先配制一定溫度下的飽和醋酸鈉溶液，然后在溶液中慢慢加入無水乙醇，冷卻，即可得到固體酒精。）

[Experiment]：請學生上來根據幻燈片顯示做實驗。做好后，點燃固體酒精。

[幻燈片顯示]：酒精的熔點是－117.3℃，固體酒精并不是固體狀態的酒精，而是醋酸鈉與酒精形成的凝膠。醋酸鈉易溶于水而難溶于酒精，當兩種溶液混合時，醋酸鈉在酒精中形成凝膠而析出，液體逐漸由渾濁到稠厚，最后凝聚成為一整塊，這就是固體酒精。

[第三部分 小結]

[在這三個應用中，有些混用物質是有用的，有些是有害的，鼓勵學生努力學習，實現自己的夢想，與開頭呼應。]

Teacher: In the three experiments ,we all mix two different substances together. Some do good to us, some do not. Whether it is useful or not depends on the way we use. So I hope you can make good use of your knowledge and make great contributions to our society. I'm sure you all can make your dreams come true!

4自己的體會與反思

我校雙語教學還處于起步階段，在這個階段，關鍵要先激發學生對雙語學習的興趣，為此我設計了多個學生活動的環節，如表演、猜謎等，化抽象為形象，課堂氣氛較活躍。

利用化學學科得天獨厚的優勢，我充分發揮了實驗的作用，這樣比直接說教效果好。

本節課的目的是想讓學生掌握幾個較常用的化學術語的英語表達，而有些化學原理的解釋，全用英語解釋，擔心影響學生的理解，所以選擇了用幻燈片以中文形式解釋。

學生的表演很精彩，讓我深受感動。我感受到了他們的青春活力、他們的創造力以及他們的表演能力；我也深深感到要讓學生喜歡這門課，教師要多開發一些與生活實際緊密相連的知識，讓學生覺得學有所用，求知欲會更強。

不足的地方：原理的解釋用幻燈片顯示或教師自己解釋較多，可以多設置一些小問題，嘗試由學生用英語來討論，真正達到雙語教學的目的。