Introductionandwriting






tongs crucibledissolve


solid/liquid/gas


balanceBunsen burnertest tubetest tube


1. (a) Water exists as a solid, a liquid and a gas. (b) Water exists as a solid and a liquid only.2. (a) When you heat a metal, it expands. (b) When you heat a metal, it contracts.Guess, listen and check the answer. Listening


3. (a) Steel is a mixture of iron and other substances. (b) Steel is a mixture of iron and oxygen.4. (a) Two-thirds of the earth’s surface is water. (b) 50% of the earth’s surface is water.




7. (a) The earth is twice as large as the moon. (b) The earth is forty-nine times larger than the moon.


1) air — gas — oxygen 2) contract — expand 3) earth — sun — moon 4) gas — liquid — solid


液体2.expand: vi.
使...d 胀 Metals expan膨when they are heated. 3. contract vi.
收缩Metals contract as they get cooler. 4. substance n.
物质 5. mixture n.
混合物6. oxygen
氧气7. electricity n.
电
1.liquid :


1.Which of the above are natural? 2. Electricity, iron, some metals and air are natural. 2. Which are man-made? Steel, some metals and glass are man-made. electricity iron metal steel air glass


3. Which can be both? Electricity and some metals (alloys for example) can be man-made and occur naturally.




5. The distance of the sun from the earth is 150,500,500 kms.6. The earth is 4.6 billion years old.7. The earth is forty-nine times larger than the moon.


Listening and writing You will hear a conversation in which a teacher helps a student do an experiment. Read the Aim below and predict the Result.Aim: To find out if there is a change in weight when the metal magnesium burns in air.Result:__________________________.


Aim: ____________________________ ____________________________ ____________To find out if there’s a change in weight when magnesium burns in air. Listen and complete the description of the scientific experiment.


Apparatus: _________________________ ___________________Method: ___________________________ ___________________________ ___________________________ ___________________________ ___________________________ ___________________________ _______________________Magnesium, Bunsen burner, a balance, a crucible. First, put the magnesium in the crucible. Then put the crucible on the balance and weigh it. Next, heat the magnesium. Light the Bunsen burner and hole the crucible over it. Finally weigh the magnesium again.


Result: _____________________________Conclusion: ________________________ ________________________ ____It weighs a little more than before.There is a change in weight when magnesium burns in air.


Listening text(Mr C=Mr Chen, Z.K=Zhou Kai, L.K= Li Kang)Mr C: OK, boys and girls, we’re going to do an experiment. Come a bit closer. The closer you are, the more you’ll see! That’s right! Now, what’s the aim of this experiment, Zhou Kai?


Z.K: We want to find out if there’s a change in weight when magnesium burns in air.Mr C: That’s right. So what do we need first?Z.K: Um… We need some magnesium. How much do we need? What about this piece? Is this piece OK?


Mr C: No, we need rather more than that—about two and a half grams. We need a piece which is much bigger than that. Z.K: OK… And we need a Bunsen burner … a balance … and a crucible to put the metal in … Here they all are... Where do we go from here?


Mr C: Well, first, put the magnesium in the crucible. Then put the crucible on the balance and weigh it. Z.K: OK…Mr C: How much does it weigh? Take a look, everyone. Is it any heavier?Z.K: Um… It weighs two and a half grams. Do you want me to write that down?


Mr C: Yes, write it down. What next?Z.K: Yes… Um, next, we’re going to heat the magnesium. So I light the Bunsen burner. After that, I hold the crucible over it… Oh look, it’s burning with a white light! It’s getting brighter and brighter!


Mr C: It’s pretty, isn’t it? Keep the noise down, boys and girls, please.Z.K: Um… lastly, we need to weigh the magnesium again… It weighs four grams now. Mr C: So what does that tell you?Z.K: It weighs a little more than before.




Mr C: You’ve got it! Well done! So now, let’s do the same experiment with copper. Come along. Li Kang, it’s your turn now. What do you think will happen if you heat copper?Z.K: I think it’ll be a lot heavier than magnesium. Shall I begin?Mr C: Yes, go ahead!


1. “Where do we go from here?” means ______. A. What shall we do next? B. Is this the right way?2. “Keep the noise down” means____. A. Don’t talk B. Talk quietly Choose the correct meaning.


3. “You’ve got it” means ________. A. You’ve understood B. You have something 4. “Go ahead!” means ________! A. Go away B. Begin 5. “It’s your turn” means _______. A. You’re next B. Turn round


Decide what the aim of the experiment is. Listening and speaking on Page 95The aim is to write a secret message.Put the stages in the correct order.










1. 2. 3. 4. b squeeze lemon and pour the juice into a containerf dip your pen into the juicea write your message on a piece of paperg blow on the paper to dry the lemon juice


5. e light a candle6. c heat the paper in the candle flame7. d the message appears when the juice reacts with oxygen and produces brown oxide


Listening text The aim of this experiment is to write a secret message with invisible ink. For the experiment, you need the following things: a lemon, a small container, a pen, some white writing paper, a candle and some matches.


First, squeeze the lemon and pour the juice into a container. A glass or a cup will be fine.Next, take your pen and dip it into the lemon juice then write your message in large letters on a clean sheet of white writing paper.


After that, blow on the paper to dry the lemon juice. Your secret message is ready and you can exchange messages with another student. Next, light a candle with the matches. Finally, hold the paper near the candle flame.


The message will gradually appear on the paper. The words are a light brown color. The message appears on the paper when you heat it because the lemon juice reacts with oxygen in the air. This reaction produces a brown colored oxide which you can see.