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111Unit 4 Astronomy: the science of the starsTeaching goals 教学目标1 Target language目标语言a重点词汇和短语preparation, instruction, unexpected, a set of, pay attention to, as well asb交际用语Practice giving instructionsPlease look at/ listen toPlease check thatYou needPlease pay attention toDont forget toYoud betterMake sure youWatch out forYou mustnt2 Ability goals 能力目标a. Enable the Ss to make a list of things that they need.b. Enable the Ss to talk about giving instructions.c. Enable the Ss to play different roles in a conversation.3 Learning ability goals 学能目标a. Learn how to make a list of things that they needb Help the Ss learn how to talk about giving instructionsc. Enable the Ss learn how to play different roles in a conversation.Teaching important and difficult points教学重点难点a. Teach the Ss how to how to talk about giving instructions b. Help the Ss to learn how to play different roles in a conversation.Teaching methods教学方法a. Pairs work and group workb. Discussion and cooperative learningTeaching aids教具准备1 A computer 2 A projectorTeaching procedures & ways教学过程与方式Step I Revision Ask some of the Ss to read his / her passage about gravity.One possible passage: Sir Isaac Newton: The Universal Law of Gravitation There is a popular story that Newton was sitting under an apple tree, an apple fell on his head, and he suddenly thought of the Universal Law of Gravitation. As in all such legends, this is almost certainly not true in its details, but the story contains elements of what actually happened. What Really Happened with the Apple?Probably the more correct version of the story is that Newton, upon observing an apple fall from a tree, began to think along the following lines: The apple is accelerated, since its velocity changes from zero as it is hanging on the tree and moves toward the ground. Thus, by Newtons 2nd Law there must be a force that acts on the apple to cause this acceleration. Lets call this force gravity, and the associated acceleration the accleration due to gravity. Then imagine the apple tree is twice as high. Again, we expect the apple to be accelerated toward the ground, so this suggests that this force that we call gravity reaches to the top of the tallest apple tree. Sir Isaacs Most Excellent IdeaNow came Newtons truly brilliant insight: if the force of gravity reaches to the top of the highest tree, might it not reach even further; in particular, might it not reach all the way to the orbit of the Moon! Then, the orbit of the Moon about the Earth could be a consequence of the gravitational force, because the acceleration due to gravity could change the velocity of the Moon in just such a way that it followed an orbit around the earth. This can be illustrated with the thought experiment shown in the following figure. Suppose we fire a cannon horizontally from a high mountain; the projectile will eventually fall to earth, as indicated by the shortest trajectory in the figure, because of the gravitational force directed toward the center of the Earth and the associated acceleration. (Remember that an acceleration is a change in velocity and that velocity is a vector, so it has both a magnitude and a direction. Thus, an acceleration occurs if either or both the magnitude and the direction of the velocity change.) But as we increase the muzzle velocity for our imaginary cannon, the projectile will travel further and further before returning to earth. Finally, Newton reasoned that if the cannon projected the cannon ball with exactly the right velocity, the projectile would travel completely around the Earth, always falling in the gravitational field but never reaching the Earth, which is curving away at the same rate that the projectile falls. That is, the cannon ball would have been put into orbit around the Earth. Newton concluded that the orbit of the Moon was of exactly the same nature: the Moon continuously fell in its path around the Earth because of the acceleration due to gravity, thus producing its orbit. By such reasoning, Newton came to the conclusion that any two objects in the Universe exert gravitational attraction on each other, with the force having a universal form: The constant of proportionality G is known as the universal gravitational constant. It is termed a universal constant because it is thought to be the same at all places and all times, and thus universally characterizes the intrinsic strength of the gravitational force.Step II PresentationT: Do you remember the conversation between Li Yanping and Professor Wallis?S1: Yes.T: We all know that space walk is difficult and dangerous. What should an astronaut take with him?S2: oxygen can.S3: spacesuit.S4: gravity boots.S5: water system.S6: special food.S7: special ropes.T: Great! Do you know the usage of them? Now discuss them with your partner according to the form on Page31. You can refer to our listening material on Page65.When Ss discuss. Teacher walk around the classroom to give them some help.Step III Speaking (Page31)(After a few minutes.)T: Have you finished? Now speak one or two sentences for each equipment you should take. Sa: I will take water with me in my spacesuit in order to warm or cool me if its too cold or too hot.Sb: I will take oxygen can on my back in order to help me breathe oxygen in space.Sc: Ill wear spacesuit. t can protect me from many dangers. It can carry many necessary things in or on it.Sd: Ill take space buggy in order to travel on the moon.Se: Ill take a rope to tie me to the spaceship, or Ill fly away.Sf: Ill take special food so that I can eat easily, because the food will float in space.Sg: Ill wear special sunglasses in order to protect my eyes.Sh: Ill take space camera in order to take photos.T: Wonderful! Anything else?Si: Ill wear space boots in order to walk there.T: Very good. Youve done an excellent job! Do you know how to fill in the form now?Ss: Yes. T: Now look at the screen and check your answer.Sample answer:To keep you coolSpaceship with water to cool youto help you breathe oxygenOxygen tanks to carry on your backClothes for exercisespacesuitTo travel on the moonSpace buggyTo protect your skinSpacesuit To stop you flying off into spaceA rope to tie you to the spaceshipTo stop your food from floating awaySpace food that you can eat more easilyClothes for walking on the moonSpacesuitTo give shadeSunglasses in your spacesuit helmetTo take photographsSpace cameraStep IV Talking (Page62)The task asks the students to work in pairs and give a friend a number of “does” and “donts” for going into space. They need to make suggestions using the phrases that they have been given to help them. When they have worked out the advice they can write the suggestions down and read them out to the class.Show the useful expressions Please look at/ listen toPlease check thatYou needPlease pay attention toDont forget toYoud betterMake sure youWatch out forYou mustntT: Now discuss it in pairs. Then I will ask some pairs to read out their instructions.Sample dialogue:S1: Im going to visit a comet. Im leaving tomorrow.S2: How exciting! Please check that you have got the correct sort of spacesuit. You need the kind that will keep you warm if its too cold.S1: Of course!S2: Make sure you know all the safety rules. Its not safe to stand on a comet or get too close. There is always a strong wind in space.S1: I wont leave the spaceship except that I take photos.S2: Photos? Just think of the dust in the air. It will make taking photos very difficult.S1: Well, Ill take some anyway.S2: Watch out for the space wind! It can be very dangerous.S1: Yes, I know that.S2: Dont forget to watch the time as you leave the earth. Please pay attention to everything your space guide says. Dont go off on your own. Look at your temperature on your spacesuit all the time. If its too low you need to warm it up and if its too high you need to cool it down. Anyway, have a good trip!S1: Thank you. I will.Step V Speaking Task (Page67)The purpose of this task is to use the information the students have gained from the listening text and reading passage in a new situation. They are going to interview the astronomer in our story, Li Yanping, for a newspaper. So in pairs the need to work out some questions to ask him. Each of the pairs needs to think of three different questions. And try to find the answers.Questions and answers:1.What was the most unexpected thing you found out about black holes?The black hole threw out material as well as ate objects.2.How did you know you had got close to a black hole?You can see things disappear into what appears to be an empty space. Thats a black hole.3.What was the most frightening thing that happened to you on this journey?When the gravity of the black hole was pulling us to its mouth, and then the spaceship moved round the hole and began to go faster and faster into it; I was terrified because I thought we would be eaten by the hole.4.Why did your watch move slower when your spaceship moved around the hole?Im not clear yet.5.Have you found something new about black holes?Yes. I thought black holes only eat some objects, but in fact they also spit objects out.Step VI Homework:Prepare for writing a passage about your idea or hopes for traveling in space.111
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