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难点：通过示范，实验操作来突破难点。
教学思路:
本课以“让蜡烛持续燃烧”为题，以一个有趣的实验为主线，既渗透了有趣的科学知识，又练习了用英语表达次序。从实验的材料，到实验步骤，再到实验结论，环环相扣，层次分明。课堂设计做实验，激发和培养学生的学习兴趣，鼓励学生大胆实验，勇于探索，热爱科学。
教学准备：
A candle, a candle holder, a big glass jar, a shallow dish, some water, a lighter
教学过程：
Step1 Warming up
1 Greeting each other
2 Free talk (Present an experiment that we did in lesson 25 ,and describe it in English.)(给一个模式，让学生们更容易描述这个实验。)
3 Lead the new lesson
Today we will learn to do another experiment :keep the candle burning!
Step 2 Check yourself.(检查学生们的预习情况，以便更好的开展英语教学。)
Step 3 Presentation
What do we need? Watch and learn some new words. (实物展示,形象生动)
We need a candle ,a candleholder,a big glass jar ,a shallow dish ,some water , matches or a lighter .(besides oxygen,examine.)
Practise the new words.(加深对于生词的记忆，为了更好的描述实验。)
What do we do ? Listen and put the sentences in correct ordle.
Read the text and fill the blanks.
Let’s do the experiment together!Put the candle in the candle holder.Put the candleholder in the dish.Fill the dish half full of water.Light the candle with a or a lighter. What can you see? The candle is burning. the candle burn for two or three minutes. Then carefully put the jar over the candle until the top of the jar rests on the dish. As the candle burns, it up oxygen in the air. When the candle stops , it has used up all the oxygen in the jar.The water inside the jar and fills about of the jar.This is because about one fifth of the air is made up of oxygen.
What can we see? The candle stops burning. The water rises up.
Step4 Read and think
1 why does the candle stop burning?
Because it has used up the oxygen in the air.
Why does the water rise?
Because the force outside the jar is stronger than the force inside the jar.
3 How far does the water rise?
The water rises and fills about one fifth of the jar.Because about one fifth of the air is made up of oxygen ,
Step5 Group work. Let’s do the experiment in groups and write the experiment report.
Step 7 Summary and homework.