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T:Good question.Who’d like to answer his question?(Nobody answers his question.) T:Perhaps it is a little difficult to answer it immediately.Now you can have a discussion about the reason for it,using what you have learnt in physics. (Teacher lets students discuss in groups of four.A few minutes later,teacher checks their answers.) T:Who wants to explain the phenomenon? S6:I think water is heavier than oil,so vegetable oil is on the top of the water. T:Who has different ideas? S7:I think we should say that the density of water is higher than the density of vegetable oil,so the result formed. S8:What’s the meaning of “density”? S9:“Density” is “密度” in Chinese. T:Do you agree with the reason for it? Ss:Yes.We agree with the idea. T:As we know,if we pour milk and water into one glass,we can’t tell where water is and where milk is.But just now we poured oil and water into one glass,it is so different now.Do you know why? Ss:Because oil can’t dissolve in water,but milk can. T:Very good.Let’s make a summary about the experiment.If we pour vegetable oil and water into one glass,the liquid will become two parts because oil can’t dissolve in water.Since the density of water is higher than vegetable oil,vegetable oil will be on top of the water.Is that clear? Ss:Yes. T:Would you like to watch another experiment? Ss:I’d love to. T:OK.I’ll perform the next experiment by myself.Look at me.I have a glass of water.Now I’ll cover it with a piece of thick paper.Attention,please. (Teacher puts one hand on the paper and turns the glass upside down.Then teacher slowly takes his/her hand away from the paper.) T:What can you see? (责任编辑：admin) |