39ArticlesofBasicTOEFLListening所有听抄文本

39ArticlesofBasicTOEFLListening所有听抄文本 第一篇 , Hi, Brad, thanks for coming in. , No problem. What did you want to see me about? , Well, I saw your mid-semester grade report, and there was something of a problem on it. , You mean my history class? , Yes, exactly…You do understand that there is a problem in your history class, don’t you? What is the problem? You are doing fairly well in your other classes, but in history you are, frankly, not doing very well at all. Your grades in your other classes show that you are capable of doing good work. What is the problem in history? , Well, history’s so early in the morning. , It’s nine o’clock; that’s not so early. , It seems early to me. , So, set you alarm clock…This brings up a question, by the way… you do get up and go to history class, don’t you? , Usually. , Usually? Since it’s a class you’re not doing well in, you should be there all the time. , I’ll try. , And take a seat in the front of the class near the professor so you can get involved in the class. , But it’s such a big class. You have to get there early to get a seat in the front. , Well, maybe you should try getting there early… , I’ll try… , And get there early for every class… , I’ll try that, too. , Now, is that your only problem in the class, that you miss class sometimes and get there late other times? , No, not exactly. , What else is a problem? t do too well on the exam. , Well, I didn’t, uh, I…I didn’ , And what was your problem, do you think? , I studied for the exam, I really did…But there were a lot of questions on the exam that weren’t in the class textbook, in the chapters that were covered on the exam. At least half the questions on the exam weren’t from the book. , Do you understand why? , I think there must’ve been a lot of questions from the lectures, stuff that wasn’t covered in the text. , Are you sure? , No, but I think so. , Well, maybe you should check with the professor and find out if that’s the case. , OK. , And if it is, maybe you should concentrate on taking good notes during the lectures. , OK. , And of course you should be in class all the time to take good notes. , That’s for sure. , OK, so check back with me in a couple of weeks, and let me know how you’re handling this. , I’ll do that. 1 第二篇 , Today, we’re going to review the characteristics of sleep, in both humans and other types of living beings. We talked about this some in the last class, and you should have done the reading, so this should all be clear to you. First of all, what are the main characteristics of sleep? Let’s talk about this diagram. What happens to the human body when a person is sleeping? Uh…can you start this off for us, Pam? , Well, during sleep, the, um, muscles relax, both breathing and heart rate slow down, and…brain waves change. , Exactly. Now, let’s look at these drawings of brain wave patterns. Ron, can you explain how brain waves change? , I think so. The brain of a person who’s awake and relaxed gives off about ten small waves per second, like in the drawing on the left. But it’s different in deep sleep. , What’s different about deep sleep? , Well, I think that in deep sleep, the, uh, brain waves become much slower and larger, like in the drawing on the right. t sound quite sure of your answers, Ron, but you’ve got them exactly right. Brain waves are the , Well…you don’ slowest and largest during the first few hours of a period of sleep. This is called the period of slow-wave sleep. Are brain waves always large and slow during sleep? Nancy? , No, um, there are periods of small and fast waves at intervals during a period of sleep. These short and fast waves are similar to the brain waves of a person who’s awake. , And what happens to the eyes during these periods of fast brain activity? , The sleeper’s eyes move rapidly. This is called “rapid-eye-movement sleep” or REM sleep. , Yes, Pam, exactly. And what other name does the period of REM, or rapid-eye-movement, sleep have? , REM sleep is called “dreaming sleep” because this is when dreaming occurs. , OK, let’s stop for a moment and make sure it’s all clear so far…We’ve seen that when a person sleeps, there’re different types of brain-wave activity. There’re periods of large, slow brain waves during deep sleep, and there are periods of small, fast brain waves during REM, or dreaming, sleep. Now, we’re going to compare human sleep patterns with the sleep patterns of certain animals. What can you tell me about the sleep patterns of mammals, Ron? , Mammals seem to experience true sleep, with changes in brain-wave patterns. They have periods of slow-wave sleep. , And what about reptiles and fish? Nancy? , Reptiles also experience sleep with changes in brain-wave patterns, but they don’t seem to have periods of dreaming sleep. Fish have periods when they become less aware of their surroundings, but, um, there’s no scientific evidence of changes in brain waves. , Excellent. Now, Pam, let’s see if you can summarize the information for us. Which types of animals seem to experience changes in brain waves while they’re sleeping? , Humans, of course, and also mammals, birds and reptiles. Fish don’t seem to experience changes in brain waves. , And what about periods of dreaming? , Again, humans, of course, experience periods of dreaming, and most mammals seem to experience the same type of dreaming, with periods of dreaming sleep and periods of slow-wave sleep. Birds may experience short periods of dreaming, but reptiles and fish don’t. , That’s very good. That’s all for today. 2 第三篇 , I see that a comprehensive exam is required for my major, and I’m not exactly sure what a comprehensive exam is. , A comprehensive exam is an exam that you take in the final quarter of your studies. Its purpose is to determine your overall competency. , How is this comprehensive exam different from a final exam? , A final exam covers all the material taught in a specific course; a comprehensive exam, on the other hand, covers all of the materials taught in the entire program. , And it’s true that comprehensive exam is required for my major? It’s not an option? t required for all majors at this university, but it is required , No, it’s not an option. A comprehensive exam isn’ for your major. Sorry, it’s not optional. 第四篇 , Professor, I have a question about taking the engineering course that you’ll be teaching. I already took this course once, but I didn’t do very well in it, and I’d like to take it over again. , Why do you want to try it again? Do you think you can do better this time? , Well, I understand about half of the material last time, and if I concentrate on the rest of the material, I think I can do much better next time. , It’s…um…possible to repeat a course to try for a higher grade, as long as the appropriate form is filled out. , I’ve got the form right here, and I’ve already filled out most of it. All I need is your signature at the bottom. , That’s fine. You really do seem prepared. Give me the form, and I’ll sign it. 第五篇 , I have a problem, and I hope you can help. , What’s your problem? , I haven’t received my grade report from last quarter, and my friends have already received their grade reports. , Grade reports from last quarter were mailed our two weeks ago. You haven’t received yours yet? , No, I haven’t. , Did you move in the last quarter? Has your address changed? Um…maybe the grade report went to the wrong address. , No, I’m still in the same place. I haven’t moved. The address should be accurate. , And did you take all of your final exams? If you missed an exam, then your grade report would be held up. , No, I took all my exams… , Then, uh, you should’ve received your grade report by now. Give me a moment, please, and I’ll look your grade report up in the computer system and see if I can figure out what the problem is. , Thanks very much for your help. 第六篇 , OK. Let’s see where we are on this project for geography class. Our presentation’s in two days, and I hope we’re almost ready. 3 , I hope so, too. We were each going to look up information about a different lake—with an emphasis on how each lake was formed—and we’ll each present information on that lake to the, to the class. My job was to look up information on Lake Superior, and I’ve done that. , I’ve done my research on the Caspian Sea. , And I’m ready with information about Lake Baikal. , Great. I’ll go first. I’ll be discussing the Caspian Sea, which is the largest inland body of water in the world. The Caspian Sea is a saltwater lake between Europe and Asia. It is believed that this lake was originally connected to the world’s oceans, which would account for its saltwater content. As the Earth’s plates moved, this arm of the ocean was cut off. , Well, here’s what I found on Lake Superior. Lake Superior is, of course, one of the Great Lakes in North America, and it’s the largest freshwater lake in the world. Along with the other Great Lakes, it was formed by glaciers. Glaciers covered the northern part of North America until 10,000 years ago and were responsible for carving out the Great Lakes, including Lake Superior. , OK, now for Lake Baikal, which is the lake I’ll be discussing. Lake Baikal’s in Russia, and it was formed when the Earth’s crust broke apart at a fault. Because Lake Baikal formed over a split in the Earth’s crust, it’s a very deep lake, the deepest lake in the world. Lake Baikal’s so deep that, even though its surface area is much smaller than the surface area of Lake Superior, it could hold the water of all the Great Lakes combined. , Well, it looks like we’ve all found information about each of these lakes, and, in particular, how they were formed. Now we need to talk about how we can present the information to the rest of the class. 第七篇 , Today, instead of lecturing, I’m going to start out by taking questions. You all know that the exam’s tomorrow, so today I’d like to spend time talking about whatever’s unclear to you. Yes, Anne, what’s your question? , I’ve got a question about the theories of Redfield and Espy. I understand that they were meteorologists, American meteorologists in the nineteenth century, and that they had different theories about how storms behave, but I’m…um, not quite sure I really understand the two theories. Could you explain them again? , OK. It’s true that William Redfield and James Espy were two nineteenth-century meteorologists and they had different theories on the behavior of storms. Espy argued that centripetal force was at work in storms. Anne, do you understand what direction the winds would be moving if centripetal force were involved? , I think so. Centripetal force would cause winds to move inward from all directions toward the center of the storm. But that’s not what really happens during a storm, is it? Winds don’t move inward toward the center of the storm. , That’s right, Anne. Espy’s theory was that centripetal force pushed the winds of a storm inward toward the center from all directions, but this theory hasn’t proven very accurate…Now, the other meteorologist was Redfield. Did Redfield agree or disagree with Espy? , I know that Redfield disagree with Espy, but I’m not quite sure how. , Can someone else explain what Redfield believed? What about you, Chris? , Sure. Redfield argued that the winds in a storm rotated around the center of the storm, so the winds would be moving in a circular path. And he believed that the winds moved in a counterclockwise direction, which means that they move in the opposite direction from the direction that a clock moves. , Yes, that’s correct. Is that clear to you, Anne? , So, Espy believed that centripetal force cause winds to move inward toward the center of a storm, and, um, Redfield believed that the winds in a storm moved in a counterclockwise direction. 4 , Exactly. Now, for the most important question…We’ve already said that Espy’s theory on how the winds in a storm behave wasn’t very accurate. What about Redfield’s theory? Was his theory accurate or in accurate? Anne? , I think Redfield’s description was quite close to what actually happens in a storm. , That’s right. Now, … who has another question? 第八篇 , Halley’s comet, which passes by our planet every 76 years, last come by our planet in 1986… , This comet was named after astronomer Edmund Halley who correctly predicted its return in 1758, sixteen years after his death… 第九篇 , Hi, I need to get a parking sticker. , Well, you’ve come to the right place. Let me ask you a few questions. First, are you a student? , Yes, I am. , And have you ever purchased a student parking sticker before? , No, I haven’t. This is the first time I’ve gotten a parking sticker. , OK, and do you have your student I.D. with you? , I do. , And how are you going to pay for the sticker, with cash, check, credit card, or debit card? , By check. , That’s fine. All right…all you need to do is fill out this form and write your check, give me the form and check, and then show me your student I.D. , Do I have to bring my car over here so you can put the sticker on it? , No, that’s not necessary. I’ll give you the sticker, and you can put it on your car. Just be sure to put it in the right place. , Where do I need to put it? , On the front window of the car, on the right-hand side…no, wait a minute, not on the right-hand side…it should be on the left-hand side. , Front window, left side. OK, I’ve got it. , Now, do you know about the various parking areas on campus? , Well, I’ve noticed that the parking areas on campus are marked with different colors, but I’m not sure what these different colors mean. , It’s really very easy. The parking areas are marked with two different colors. The blue parking areas are for faculty and staff, and the yellow parking areas are for students. , And I’m a student, so that means I can park in the yellow parking areas and not the blue ones. , That’s exactly right. Now, let me get that sticker for you. 第十篇 , We need to get going on our class project for drama class. We have to present a scene from Our Town, in costume and with props. Our performance is only in three weeks, and that’s not very much time for all we 5 have to do. , Let’s see. We’ve already decided on a scene from Our Town. , And we know who’s going to play each part. Bill, you’re going to be the Stage Manager—that’s a big part in this play. Tina, you’re going to play Emily, and I’m going to play George. We’re going to do a scene from the part of the play that takes place before George and Emily’s wedding. I’ve already started learning my lines. What about you two? , I’ve already started working on my lines. , And I’m familiar with mine, too. I think we’re ready to read through the scene together. , Why don’t we discuss what we’re going to do about costumes and props first, and then we can run through the scene together. , That sounds like a good idea to me. , I think so, too. 第十一篇 , All of you are enrolled in this introductory education course because you want to become teachers. I’d like to introduce this course with a little information about the life of a teacher a century ago. I hope you’ll understand this information about early teachers, and I think you’ll appreciate how much the life of a teacher has changed over the past century. , Early in the twentieth century, the life of a teacher was quite different from what it is now. There were very strict rules that governed every aspect of the teacher’s life. The rules weren’t just about how a teacher could conduct herself in the classroom and on the school grounds. There were also numerous rules that governed just about everything a teacher did. , Here are some of the rules. Teachers had to follow, um, strict rules about their appearance; they were sometimes told not to wear colorful clothing, not to dye their hair or wear it loose, and not to wear their skirts above the ankle. Teachers’ whereabouts during after-school hours were also strictly regulated; there were rules forbidding teachers to go to bars and to ice-cream parlors; there were rules requiring teachers to be home after eight o’clock in the evening; and there were some rules forbidding them to leave town without permission. Just about any action a teacher wanted to take could be regulated. Teachers could be forbidden to smoke or to drink; they were also sometimes forbidden to spend time with men or to marry if they wanted to remain teachers. 第十二篇 , OK. So, the next type of mineral we need to talk about is iron pyrite. , Iron pyrite? Isn’t that what’s also called fool’s gold? , Yes, it is. , Why is iron pyrite called fool’s gold? , It’s called fool’s gold because it can look sort of like gold, and sometimes people who found iron pyrite thought they’d found gold. , So iron pyrite kind of look like gold? What exactly does it look like? , It can be shiny golden in color, but its crystals have a different shape from, from golden crystal. Iron pyrite crystals are cubical in shape. Crystals of gold aren’t. , How does iron pyrite get its shiny golden color if it’s not gold? 6 , I know the answer to that…iron pyrite gets its shiny golden color from the mix of elements in it, the elements it contains. , Iron pyrite’s made from a mix of elements? , Yes, Iron pyrite’s a compound of iron and sulfur, so it’s very different from gold because it’s made of this compound. , And it’s also quite different from gold in how it reacts to heat. Iron pyrite has a very strong reaction to heat. , Why? What happens when iron pyrite heated? , When iron pyrite heated, it smokes and develops a strong, uh, an awful odor. , And gold doesn’t have that kind of reaction to heat? , No, it doesn’t. , Do you know where the name “pyrite” came from? , I think I know that. It came from the Greek word for fire, didn’t it? , Yes, it did. If you strike iron pyrite with metal, then it produces sparks. Some ancient cultures used to use iron pyrite to start fire. They couldn’t have used gold that way. , So iron pyrite did have some use, even if it really wasn’t gold. 第十三篇 , Thanks for seeing me, Dr. Barton. , No problem. It’s my office hour…What did you want to talk about? , I wanted to discuss the topic I’ve chosen for the paper I’m supposed to be writing for your anthropology course. The topic I’m thinking about is a bit unusual. , Oh you know, it has to be related to some aspect of anthropology that we’re studying…What topic did you have in mind? , I wanted to write about a test used by the Roman military to test soldiers’ eyesight. , Hmm…an eyesight test used by the Roman military? Are you sure this is related to our anthropology class? ...Well, tell me about it…What is this eyesight test that the Roman military used? , Well, it was a test that the Romans used to determine if their soldiers would fight as foot soldiers on the front lines or as archers behind the front lines. Roman soldiers were required to undergo certain tests to determine their ability to perform as soldiers. One of their tests was simply to count the stars in the constellation, the Big Dipper. This test determined the acuity of their vision. See. Look at this picture of the Big Dipper. You can see the seven stars in the Big Dipper. The star at the bend of the handle of the Big Dipper is called Mizar, and Mizar is a binary star. If you look closely, there’s a second star called Alcor next to Mizar. If a Roman soldier’s eyesight was good enough to see Alcor, he could fight as an archer. If he couldn’t see Alcor, he had to fight on the front lines as a foot soldier. , So this eye test was based on the ability of the soldier to see Alcor next to Mizar. , Yes, exactly. , Well, that’s a very interesting test, but I’m not sure that it’s related to the material in our anthropology class. Well, let’s put it this way…how would you relate this to the material in the anthropology course? , I’d relate it to the idea of “survival of the fittest”. , Um…interesting…and how would you relate it to this concept? Survival of the fittest has to do with the idea that those who’re strongest or have some other physical or mental advantage will be more likely to survive. , Well, this test for eyesight was used not only by the Romans but also other groups of people for hundreds of years. The interesting point is that over time more people have been able to pass the test, and the fact that 7 more people have been able to pass this test over time has been attributed to survival of the fittest. It was certainly true for Roman soldiers that those who passed the test had a better chance of surviving for longer. , And why is that? Why did Roman soldiers who passed the test stand a better chance of surviving longer? , Well, soldiers with better eyesight weren’t on the front lines. Those with worse eyesight were sent to the front lines and, more often than not, were killed on the front lines. Archers stood a better chance of survival and were around to father children, who would also tend to have better eyesight than those who failed the test. This is what supports the concept of survival of the fittest. , Hmm. That’s an interesting idea. As long as you concentrate on the idea of survival of the fittest in your paper and use this example of an eye test to support the concept, I think you would have a solid paper. , That’s what I’ll do then. Thanks, Dr. Barton. 第十四篇 , Professor Roberts, I have a question for you about the assignment. , OK, if it’s a short question. , It is. The assignment on the syllabus lists pages 101 through 120 in the text, and the last page of the assigned reading is a list of questions. I was wondering if we were supposed to read through the questions and just think about the answers or actually write out the answers to the questions. , Well, you don’t need to write out neat and formal answers to the questions, but you should be really familiar with the answers because we’ll be talking about the questions during class and I expect you to have answers ready. , You mean, we don’t need to turn in written answers to the questions? , That’s right, but you might want to jot down notes about your answers so that you can refer to them during our discussion. 第十五篇 , Excuse me. Can you help me, please? , That’s why I’m here. What do you need? , I need to find a specific magazine, and I’m not sure where to look. , How old is the magazine you need to find? Is it a recent magazine—less than a year old—or is it an older magazine? , You need to know how old the magazine is to find it? , That’s why I asked. The more recent magazines—those that are less than a year old—are in the Magazine Reading Room, on the second floor. But after a year, magazines are bound together and put in hard covers, and the bound magazines are on the third floor. , Well, the magazine I want to find is more than a year old, so that means that I need to go to the second floor, oh, excuse me…what am I saying? ...The third floor. , That’s right. The third floor. , Thanks for your help. I really appreciate it. , You’re quite welcome. Feel free to come by any time. 8 第十六篇 , Hey, Sam, I have a question for you. , All you have to do is ask. , I think it’s a pretty easy question. All I need to know is how I can get a copy of my transcript. I need one for a scholarship I’m applying for. , Oh, I think I can handle that one. You need to go to the registrar’s office to get a copy of your transcript. , That’s all there is to it? I just go to the registrar’s office and ask for a copy of my transcript, and I’ll get it? , Well, it’s not quite that easy. You need to go to the registrar’s office and fill out a form, a transcript request form. Then you turn in the form with a ten-dollar fee. ll take too long. , That doesn’t sound like it’ , I hope you don’t need the transcript too soon. , I need it within a week. , Well, you may get lucky…but don’t count on it. , I really need it within a week, or else I won’t be able to turn the application in on time, and that means I won’t get a scholarship. , Well, if I were you, I’d get over to the registrar’s office immediately. And it wouldn’t hurt to explain that you need the transcript right away. But I wouldn’t count on it. I don’t think transcripts are processed that quickly. , I’ll get over there right now and see what happens. 第十七篇 , The next animal we need to discuss is the opossum. The opossum is another kind of marsupial. , A marsupial? Oh, no, I think we’re supposed to know what that is. , We are. A marsupial’s an animal that carries its young in a pouch. , Oh, that’s right. It’s like a kangaroo. , Exactly. , And young opossum stay in their mother’s pouch for what, a few days? , No, not exactly. It’s about two months. Then, when the babies are about two months old, they come out of their mother’s pouch, but they don’t go very far. For the next few months, they go everywhere with their mother. , They just ride along on their mother’s back. , So young opossums spend the first two months in their mother’s pouch and the next two months hanging on her back? , You’ve got it. Now, aren’t opossums animals that play dead? , Oh, I don’t think it’s opossums that play dead…Oh, wait a minute…Maybe it is. We do talk about playing’ possum if we’re talking about pretending that we’re asleep or dead. , Exactly. , So when an opossum’s frightened by an attacker, it doesn’t run away? , No, it doesn’t. it just rolls over on its back, kind of curls up, and pretends it’s dead. , I guess it’s just hoping the attacker will think it’s dead and will go away and leave it alone. 第十八篇 , Today we’ll be discussing the planet Venus, which is the second planet in our solar system. I’m sure you all 9 know which planet is the third planet in our Solar System. Yes, Beth? , Is Earth the third planet? , You don’t sound too sure of your answer, Beth…but, yes, that’s true. Venus is the second planet in our Solar System, and Earth is the third. Venus is almost the same size as our Earth, which is the fifth largest planet in, ah, the Solar System. The planet Venus is easily visible in the sky from Earth, although not always as a complete sphere. It goes through some phases, just like the Moon. Sometimes it’s fully visible, like a full moon, sometimes it’s half visible, and sometimes it’s only a small crescent. When do you think Venus is the brightest, when it’s fully visible or when it’s a crescent? Mark? , Well, it makes sense that it would be the brightest when it’s fully visible. , Well, things aren’t always as they seem. Try again. , You mean, Venus is actually brighter when it’s only a small crescent than when it’s fully visible? , That’s exactly what I mean…Now, does anyone know if Venus is a hot or cold planet? …What would you expect since Venus is closer to the Sun than our planet is? , Since it’s so close to the Sun, I think it would be very hot. , And it is. The temperature there can reach almost to 500 degrees centigrade. What is this in Fahrenheit? …Anyone? …Come on, we’ve talked about this before. , I think that’s around 900 degrees Fahrenheit. , Yes, it is. Now, we’ve said that the temperature on Venus is quite hot, and the temperature there is hot because Venus is so close to the Sun. But that’s not the only reason that Venus is so hot. It’s also hot for another reason. Does anyone know? Could it be the atmosphere? What is its atmosphere made of? Beth? , Its atmosphere’s almost entirely carbon dioxide. , Yes, that’s right, Beth, and this type of atmosphere holds in the heat from the Sun extremely well…Now, let’s talk about the clouds that cover Venus. As you know, Venus is visible to us on Earth, but it’s not actually the planet that we see; it’s the clouds. The surface of Venus can’t be seen, even with a telescope, because of the clouds that surround the planet. What can you tell me about the clouds that cover Venus? , Uh…the clouds around Venus? , Yes, I’m asking about the clouds around Venus. I want to know about the clouds around Venus. , Do you want to know what they’re made of? They’re made of carbon dioxide. No…wait a minute. The atmosphere’s made of carbon dioxide…The clouds are made of sulfuric acid. , That’s right. The clouds on Venus are actually made of sulfuric acid. These clouds help to contribute to the brightness of Venus in our sky. When Venus appears to shine so brightly, it’s because the light of the Sun is reflecting off Venus’s clouds of sulfuric acid. 第十九篇 , Do you enjoy playing chess? , Yes, I really do. , Well, you might think about joining the chess club. I belong to it, and I think you might really enjoy it, too. , What does the chess club do? , The members get together once a week for friendly competitions. Then each semester, the three best players from the club compete in a tournament with players from other school. , The meeting once a week sound like a lot of fun, but…uh…my chess playing just…uh…might not be quite up to the level of tournament play. , Well, why don’t you come with me this Wednesday and try out one of the weekly meetings? You can come to 10 the meetings for a while and then see if you’re ready to compete in a tournament in a few months. 第二十篇 , I’d like to talk with you about the number of courses you’ll be taking next semester. , I took five courses last semester, I’m taking five courses this semester, and I’m planning on taking five courses again next semester. I always like to take the maximum number of courses because I don’t mind working hard and because I want to finish my undergraduate degree as quickly as possible and get in graduate school. , I understand that you’re trying to finish your undergraduate program quickly in order to go to graduate school. However, the problem is that your grades are passable but not very high, and you’ll need higher grades to get into a good graduate school. , I definitely want to go to a good graduate school. Do you think it’s better for me to take a lighter course load next semester in order to try to get higher grades in those courses? , Well, …because you’re taking the maximum number of courses, I don’t think you have enough time to put sufficient time and effort into each of your courses. 第二十一篇 , This is an interesting assignment we have for psychology class. , Interesting? It’s going to be a lot of work. , What’s so hard about it? We just have to make up a survey questionnaire related to theories from the class. , Making up a survey questionnaire isn’t so hard. But we have to find fifty people to fill out the questionnaire and then write up a report analyzing the data. , It’ll be easy to find fifty people to fill out the questionnaire. We can do that in one afternoon at the student center. That actually sounds like fun to me. , That’s good. I don’t mind preparing the questionnaire and analyzing the data, but getting fifty people to answer the questionnaire does not seem like fun to me. 第二十二篇 , Our topic for today is Iroquois villages, and I’m going to have a rather unusual assignment for you based on this topic, so you need to listen carefully to the information. First of all, I’ll be describing an Iroquois village, and then, for your assignment, I want you to draw a village. , Excuse me, Dr. Thomas. You want us to draw an Iroquois village? , Yes, that’s exactly what I want you to do. I think this will help you to understand the efficient simplicity of the design of an Iroquois village. Now, let me describe an Iroquois village and what makes it so special. An Iroquois village consisted of a number of longhouses. Iroquois longhouses were long, single-story houses with U-shaped roofs, and they were very elegant in their simplicity. Iroquois villages were also well defended. Around an Iroquois village, there was usually a stockade, which is a defensive wall or barrier made of wooden posts. The stockade around an Iroquois village was typically hexagonal in shape, which means that it was six-sided. It had vertical wood posts around the outside of the stockade, and these posts had sharpened ends pointing upward for further protection. Now, for the assignment…your assignment is to create a pencil drawing of an Iroquois village. You can use the 11 information I just provided, and you can find more information in Chapter 22 of the text. , But, Dr. Thomas, what if I can’t draw? I’m not very good at drawing. , Well, just try your best. I want you to make a good effort. , Are you expecting just a simple drawing, or does the drawing need to be complicated? , I’d like you to do the best you can do. , Well, for me, my best might not be what you’re expecting. 第二十三篇 , OK, I think we understand how snow and rain are formed. Now we need to discuss the formation of hail, and t very clear to me. What exactly is hail? And how does it differ from snow and rain? this part isn’ , Well, it’s not really too hard to understand. Hail is really just frozen drops of rain. , That’s all it is? When I was reading about it, it seemed rather hard to understand. How is hail formed? , Hailstones develop in cumulonimbus clouds that have grown very tall. , Cumulonimbus clouds? , That’s right. Cumulonimbus clouds are very tall clouds. They can actually be as tall as six miles. Because they’re so tall, they’re much warmer at the bottom than at the top. , That’s really tall. , And sometimes air currents blow drops of water in a cloud up higher into the cloud. , Where it’s colder, so the drops freeze into ice. Do the drops fall to the earth then? , Usually not just after the trip up. Usually the drops aren’t yet heavy enough to fall to the Earth. , So the drops rise and fall a number of times within the cloud, and each time a drop rises and falls, it adds another layer of ice? , Yes, you’ve got it. , Really? This isn’t as difficult as I thought. I can understand it. , Yes, you can. A hailstone actually has a number of layers of ice on it, one layer for each time that it’s pushed up and freezes again. After it builds up enough layers, it gets too heavy. , And that’s when it falls to Earth. , Exactly. 第二十四篇 , Today we’re going to talk about a coin from early in the history of the United States. It was the first coin issued by the U.S. government, and it was issued soon after the government was established. Do you know when this was? …Any idea?...Come on, you must have some idea when this was. Yes, Sam? , Was it in the late 1700s? , That’s right, Sam. This coin was issued in 1789. It was known by two names; it was known as both the Fugio coin and the Franklin coin. First of all, can you tell me why it was called the Fugio coin? Laura? , It was called the Fugio coin because it had the word fugio on the front of the coin. Fugio is a Latin word that means “I fly.” , That’s right, Laura. And this coin was also called the Franklin coin. Why was it called the Franklin coin? It was because Benjamin Franklin was on it, wasn’t it? , No, it was called the Franklin coin because Franklin was given credit for the wording on the coin. , That’s right. Now, this is the coin we’re talking about. Let’s look at the front of the coin. Can you describe the 12 front for me? Sam? , The front of the coin has a sundial in the middle with a sun shining down on the sundial. , Yes, both a sun and a sundial are there. And what else? , Well,…uh…there’s a date along one side and …um,…there seems to be some wording at the bottom. , Sam needs some help. Who can help Sam answer the question? Yes, Doug? , The wording along the bottom is “mind your business.” This coin’s called the Franklin coin because Benjamin Franklin was given credit for the wording. , Now let’s talk about the other side of the coin. Let me describe the front of the coin for you. Oh,…excuse me,…did I say front? I meant back. On the back of the coin, there’s a large circle made up of thirteen linked circles, and in the middle of the circle are the words “We are one.” Do you understand what these words mean? , I think so, particularly with the words “We are one.” This design on the back of the coin symbolizes the thirteen original colonies linked into one country. , That’s a very appropriate idea for the first coin issued by the United States after the country won its independence. Now that’s all for today. However, I’d like to suggest that some of you might want to be somewhat more prepared for the next class. And just to check on whether or not you’re prepared, there just might be a quiz. 第二十五篇 , OK, calm down, please…. It’s time to get started…You can continue your chitchat after class. Our topic for today is hibernation. When it begins getting cold in the north as winter approaches, uh, different types of animals deal with the approach of the cold weather in different ways. Some animals move south to warmer weather, some animals ll be increase their activity to stay warm, and other animals hibernate during the cold weather. So today, we’ discussing this third category of animals, the animals that hibernate. Now, these are the animals like groundhogs and bears that go into a state of unconsciousness or semi-consciousness during the cold winter months. The first animal we’ll look at is the groundhog. The groundhog’s one of the best-known hibernators. It goes into its burrow 4 or 5 feet underground sometimes in the fall, and, uh, it doesn’t come out until spring. A groundhog stays in its underground burrow for the entire winter, without coming out. Now, because the groundhog hibernates so completely, it’s the groundhog that has achieved prominence in our folklore as the animal that’s responsible for determining whether or not winter’s over and it’s safe to come out of hibernation. You see, according to folklore, the groundhog will come out of the burrow where it’s hibernating on Groundhog Day in February. If winter’s over, the groundhog will remain out of its burrow, but if winter’s going to last for a while longer, the groundhog will scurry back into its burrow…Yes, Amanda, do you have a question? , Yes, I do. Does the groundhog have a good record, you know, about predicting whether winter’s over? , Uh, no, not really. It’s just a folktale, and the groundhog isn’t…um…batting much more than fifty-fifty. Now, back to the discussion of hibernation, with a little more emphasis on its scientific nature. We’ve discussed the groundhog, which hibernates throughout the cold weather. Other animals that hibernate in a similar fashion are bats and squirrels. Now, we’ll look at the bear, which hibernates in a different manner. 13 You see, bears don’t hibernate as completely as groundhogs, bats or squirrels. In the southern half of the United States, bears don’t hibernate at all because the weather doesn’t get cold enough for them to hibernate. In the northern half of the United States, bears may not stay in hibernation for the entire winter. They may come out of their hibernation during the winter and wander about before returning to hibernation…Yes, Tom, what’s your question? , Well, professor, I’m not…uh…exactly sure what…um…hibernation is. I mean,…how is hibernation different from sleep? , Ah,…that’s a good question, Tom, one that I’m a little late in clarifying. Hibernation is different from sleep, and these differences between sleep and hibernation are seen in body temperature and heart rate. You see, the main characteristics of hibernation, which are very different from sleep, are that body temperature and heart rate decrease significantly. When an animal comes out of hibernation, the heart rate and body temperature increase to the levels normal during waking hours. During the period when a large animal, uh…such as a bear, is coming out of hibernation, the animal’s entire body does not warm at once. The area around the heart warms up first. As the heart warms up, it begins beating at its normal rate, and it’s then able to pump blood around the rest of the body and heat up the rest of the body. These are the main points that we need to cover about hibernation. Now, we’ll take a short break before moving on to the next subject. 第二十六篇 , Today, I’ll be talking about the major rivers of the world. The four longest are the Nile, the Amazon, the Mississippi, and the Yangtze. The Nile River in Africa is the longest, at 4,145 miles in length. It flows north from the equator to empty into the Mediterranean and irrigates more than a million acres of land. The Amazon River in South America is slightly shorter than the Nile at just over 4,000 miles in length. Though it is the world’s second longest river, it carries more water than any other river. Asia also has a massive river system. The Yangtze River in China is Asia’s longest at 3,436 miles. Because the mountains at its source are at such a high altitude, the Yangtze flows more rapidly than other major rivers for most of its length. The Mississippi River is the best-known river system in North America, and it’s the United States’ chief inland waterway. However, it’s not the longest river in North America; the Missouri River, at 2,340 miles in length, is slightly longer than the Mississippi. 第二十七篇 , Today I’ll be talking about the concept of tropism as it relates to plants. Tropism, for those of you who don’t know, refers to a bending of a plant or a part of a plant in response to an outside stimulus. There are three important kinds of tropism. They are phototropism, geotropism and hydrotropism. In each of these kinds of tropism, a plant, or a part of a plant, bends in response to a different kind of outside stimulus. First, we’ll discuss phototropism. The outside stimulus in phototropism is light. When a plant is affected by phototropism, it grows in the direction of a light source such as the Sun. The second kind of tropism is geotropism. In geotropism, the outside stimulus is gravity. In a plant affected by geotropism, the affected part of the plant grows directly downward because of the pull of gravity. When a plant’s affected by geotropism, it’s often the root structure that’s affected. 14 OK. The final kind of tropism I’ll discuss today is hydrotropism. When hydrotropism affects a plant, this means that the plant is drawn toward water. A plant under the effect of hydrotropism will grow in the direction of its water source. 第二十八篇 , Today, we’re going to be talking about fossils. A basic definition of fossils is that they are the remains of plants and animals that have turned to stone, and today we’re going to be talking about how animals become fossils. The process begins when a living being dies. After an animal dies, its soft tissues break down. When the soft tissues have decomposed, only the hard parts of the body, such as the bones and teeth remain. Over a long period of time, um, the hard tissue becomes buried under layers of sediment. As more layers of sediment cover the hard tissue, it becomes buried more and more deeply. When the boned are buried deep in the earth, they come into contact with groundwater, and a change begins to occur. Minerals from the groundwater seep into the bones and, over long periods of time, the minerals eventually replace the bones. This is the actual step when fossilization occurs, when minerals from the groundwater have replaced the actual hard tissue from the original body. The buried fossilized remains, which are buried deep within the earth, may then make their way back to the surface. As the earth moves, the remains are pushed around…if they get closer to the surface, where they can be seen, or get near enough to the surface, where they can be dug out. 第二十九篇 , We need to know about Clarence Darrow and some of his more famous cases. , OK, uh, I know that Clarence Darrow was a famous lawyer. What were some of his most famous cases? , He was famous for the Eugene Debs case, and the Loeb-Leopold case, and the Scopes trail. , He was also famous for his part in resolving a coal strike. , OK, let’s go over each of these cases and make sure we understand them. The first one was the Eugene Debs case in 1895. Darrow defended Debs, who was the president of the railroad workers union, after the railroad workers went on strike. , Wasn’t the strike by the railroad workers called the Pullman Strike? , Yes, it was; it was named after the Pullman, which was a type of railroad car. , Uh, the next situation was the Pennsylvania coal strike in 1902. Clarence Darrow was asked by the president of the United States to arbitrate the coal strike. , So this wasn’t actually a trail; it was an arbitration. , That’s true. Now, there are two other trials we need to know about: the Loeb-Leopold trial and the Scopes trial. , The Loeb-Leopold trial was in 1924. This was a very famous murder trial. , And Clarence Darrow was the defense attorney in this trial? , Exactly. , Now, the last case we need to be familiar with is the Scopes trial, but I don’t know much about that. , The Scopes trial in 1925—also known as the Scopes monkey trial—was about evolution, about whether humanity evolved from monkeys. , And who was Scopes? 15 , Scopes was a high school biology teacher who was charged with breaking the law because he taught evolution in school. , And Clarence Darrow was the defense attorney in this trial? , Yes, he is. , I think we’ve covered the information we need to know about Darrow. We know about three of the trials in which he served as defense attorney. , And we also know about the strike he helped to arbitrate. 第三十篇 , Now, we’re going to review the information on various types of fractures, or broken bones. Yesterday, we talked about three types of fractures. Do you remember what they were? Clair? , They were simple, compound, and, ah, greenstick fracture. , Yes, exactly. Now, can you tell me how a simple fracture and a compound fracture differ? Are they different because of the number of fractures? Dave? , No, the difference between a simple and a compound fracture refers to how much damage there is to the tissue around the broken bone rather than the number of breaks in the bone. In a simple fracture, the bone is broken, but there’s little damage to the tissue around the, um, around the bone. In a compound fracture, the bone is broken and there’s a lot of damage to the tissue around the broken bone. , So, how much tissue damage is there in a compound fracture? Gail? , A lot. In a compound fracture, the broken bone actually comes through the skin. , So, when we talk about the difference between a simple and a compound fracture, this doesn’t refer to the number of breaks in a bone; instead, it refers to the amount of tissue damage. How do we refer to the number of breaks in a bone? Clair? , To talk about the number of breaks in a bone, we talk about a, a single, a double, or a multiple break. A single fracture means one break, a double fracture means two breaks, and the, uh, a multiple fracture means more than two breaks. , OK, I hope this distinction’s clear, that we talk about single, double and multiple fractures to refer to the number of fractures and simple and compound fractures to refer to how much tissue damage there is around the break. Now, we have just one more type of fracture to discuss, and that’s the greenstick fracture. Dave can you tell me who generally suffers from greenstick fractures? , Greenstick fractures are usually found in children. , That’s true. And what is a greenstick fracture? Gail? , A greenstick fracture means that the bone bends and maybe it breaks part of the way, but it doesn’t break all the way through. The name “greenstick” refers to a young green plant that might bend instead of breaking. , So, is a greenstick fracture a very serious fracture? Claire? , No, a greenstick fracture’s usually the least serious type of fracture because the bone isn’t broken all the way through. The compound fracture, where the broken bone comes through the skin, is the most serious type of fracture. 第三十一篇 , Can you tell me about parking on campus? I’ve just gotten a car, and I’m going to be parking on campus. I’m so glad I don’t have to be riding my bicycle to class anymore. 16 , Parking is kind of difficult on campus because there just aren’t enough spaces for all the people who want to park. You do know that if you’re going to park on campus, you’ll need a parking sticker? , A parking sticker? What kind of parking sticker? , Well, if you’re only going to park on campus once in a while, you can get a daily sticker each day that you park. But if you’re going to be parking on campus often, then you should really get a permanent sticker. , I have classes almost every day of the week, so I know what I’ve got to do. 第三十二篇 , I’m scheduled to take a placement test in math on Saturday. Is this something I really need to do? t have to. , It’s to your advantage to take the placement test, but you don’ , What’s the advantage of taking the placement test? , If you take the math placement test and do well on it, you don’t have to take the beginning math class. You’ll be able to start with an intermediate or even an advanced math class if you get a high score on the placement test. , And if I don’t take the math placement test, then I have to start with the beginning math class? , That’s right. , Well, then, …I think I can save myself an entire semester-long course if I do as well as I think I can. 第三十三篇 , Thanks for stopping by. , No problem. Why did you want to see me? , I need to go over the outline for you term paper. , The outline for my term paper?...Is there a problem. , Well, you have a good topic and lots of interesting ideas here, but the outline itself could still be better. , Well, what can I do to improve the outline? , I have two suggestions to improve the outline. First of all, you need to organize the ideas a little more clearly. , So, you think I have enough ideas, but they need to be better organized? , Exactly. And for my second suggestion, you don’t…uh…have much of a conclusion. You should really think about…uh…strengthening your conclusion. , OK, I’ll work on the overall organization and the conclusion. Then what? , Well, after you’ve improved these two areas, I’d like you to resubmit the outline, and we can discuss it some more. , And when would you like the revised outline? , Well, don’t take too long working on it. You really need to get the outline squared away so you can work on writing the paper. Let’s say within a week? You should get it to me no later than next week. 第三十四篇 , Today, I’ll be talking about the information in Chapter 22 from the text, the chapter on conifers. You should’ve read the chapter already and turned in the answers to the ten questions at the end of the chapter. Do you know what conifers are? Well, conifers are the type of trees, such as pines, that have cones instead of colorful flowers. About a third of the world’s trees are conifers, and the vast majority of conifers are found in 17 the great conifer forests of North America and Siberia. Conifers are hardy trees that have been able to survive well, and as a result, both the oldest and the biggest trees in the world belong to the conifer family. The oldest known living tree is a four-thousand-year-old bristlecone pine, which is located in California. The giant red woods, which are also found in California, are the largest trees; they can be several hundred feet tall and weigh as much as 2,000 tons. An interesting note about the giant redwoods is that, even though the trees are so large, they have relatively small cones. What is true of most, but not all, conifers is that they are evergreen with needle-like leaves. The needle-like shape of conifer leaves evolved as a reaction to drought. When compared with a flat leaf, a needle presents a much smaller surface area, which decreases the amount of water lost through the leaves. Because most conifers are evergreens, they lose and replace their needles throughout the year, rather than shedding all their leaves in one season, as deciduous trees do. That’s all for today. For next class, you should read the next chapter and do the same with it that you did with the chapter for today. See you next class. 第三十五篇 , Today, I’m going to go over the presentation you’ll be giving and what I’m looking for in them. I’m sure you’ll want to give really good presentations; the presentations are, by the way, 50 percent of your grade in the course…Did that get your attention?...That’s right. For each of you, your presentation is fully half of your grade in the course. Um, first, let me talk about the topic. This is a course about economic theory, so for your presentation I want you to choose one of the economic theories from the course and apply it to some present-day situation. This means that you need to include both the theory and the present-day situation and make it clear how, uh, how the theory is applicable to the present-day situation. And …you’ll need to include enough facts about the present-day situation to demonstrate that it provides a good example of the theory you selected. Now, let me make it clear what I expect regarding the timing of your presentations. I’m going to be very strict about the timing. You have exactly five minutes to present, not a second more. And in this five minutes you have to present both the theory and the present-day example to show how they’re related. You’ll be stopped at the end of five minutes whether you’re finished or not, and…you can believe me…if you haven’t finished all the main points of your presentation within five minutes, your grade will suffer. Then, after you make your presentation, the other students will have five minutes to question you on your presentation. The question-and-answer period following the presentation will also last for five minutes, and all of the students in the audience are expected to be involved in questioning the presenter. , Professor, what if we don’t know enough about the situation to ask questions about it? , It’s the responsibility of the presenter to provide enough information about the situation. If you’re unable to ask questions, then the presenter hasn’t done a very good job. The presentation needs to provide enough details about the present-day situation. 第三十六篇 , We certainly have a lot of study questions to review for our history exam. , Yes, we do, but we’re almost finished. We only have two more questions to go. , Only two more questions? That’s great. Let’s get going on them, and we’ll be finished preparing for this exam…Now, what’s the next question on the study list? 18 , The next question on the study list asks about famous historical places on the Outer Banks. , The Outer Banks? Where’re the Outer Banks? , Look at the map in the book. The Outer Banks are a series of islands stretching along the coast of North Carolina. , Now, the question asks about famous historical places on the Outer Banks. Can you come up with any? , Um, let’s see. There’s the Lost Colony on Roanoke. , Can you see Roanoke Island on the map? That was where the Lost Colony was located. , Wait a minute. The Lost Colony? What was the Last Colony? , The Lost Colony was the group of settlers from England that landed on Roanoke Island in 1587. When a supply ship returned there three years later, the colonists had disappeared. To this day, no one knows what happened to them. , OK, I think Roanoke Island is one good answer to a question about famous historical places on the Outer t Ocracoke Island famous for something? Banks. Now, what about Ocracoke Island? Isn’ , All I know about Ocracoke Island is that it’s where Blackbeard had his hideout. , Blackbeard, the pirate? , Yes, Blackbeard had his hideout on Ocracoke Island, early in the eighteenth century. He used to move up and down the coast from his hideout on Ocracoke and attack ships and steal their goods. , OK, so we’ve got historical places on Roanoke Island and Ocracoke Island for answers to the question. Can you come up with any other historical places on the Outer Banks? , What about the Wright Brothers? Didn’t they make their flights on the Outer Banks? , Yes, it was at Kill Devil Hills, outside of Kitty Hawk, that the Wright Brothers made their flights. , On December 7, 1903, they managed to get a power-driven plane in the air, for just a short time. But the plane was flying. , Their first flight was only 12 seconds long. They tried four flights on the same day, and by the end of the day, they got the plane to stay up for 59 seconds, almost a full minute. , OK. I think we have enough information to answer that question. We’ve got historical places on Roanoke Island, Ocracoke Island and Kitty Hawk. , I agree. Why don’t we leave the question on the Outer Banks and move on? , Good idea. Only one more to go. We’re almost there. 第三十七篇 , Today, we’re going to talk about phyllotaxy. Phyllotaxy is a scientific term that refers to the arrangement of leaves on the stem of a plant. On most plants, leaves are arranged in a definite pattern. It’s very unusual for a plant to have randomly placed leaves. One of the main reasons why the leaves on a plant stem are arranged in an orderly way is to ensure that each leaf is exposed to the maximum amount of light with a minimum amount of interference from other leaves. The first of leaf arrangement is the alternate arrangement. You can see this type of leaf arrangement in the diagram. In this type of leaf arrangement, there’s only one leaf at each node, and a node, by the way, is the spot where the leaf’s attached to the stem. The next type of leaf arrangement is the opposite arrangement, which you can see in the diagram. In this type of leaf arrangement, there’re two leaves at each node, and these two leaves are opposite each other on the stem. This type of leaf arrangement isn’t as common as the alternate arrangement, with one leaf at each node. 19 Where was I? Oh, OK. The last type of leaf arrangement that we’re going to look at is called the whorled leaf arrangement. This type of leaf arrangement is the least common of all. It isn’t as common as either the opposite or the alternate arrangement. In this type of arrangement, in the whorled arrangement, three or more leaves are attached to the stalk of the plant at the same node. In the diagram, you can see three leaves at the same node, but it’s also possible for there to be more than three leaves at the same node, and the leaf arrangement would still be considered a whorled arrangement. Now,…I hope you’ve been paying careful attention to this information about phyllotaxy,…because I…um…have an assignment got you that’s a bit different from the homework assignments you’ve had so far. Your assignment is to visit the university’s botanical garden. Were you aware that this university has quite an extensive botanical garden? In the botanical garden, there’re examples of many different kinds of plants, and each plant is labeled with the name of the plant as well as other information about the plant. For your assignment, you are to find three examples of each of these different types of leaf structures, write down the names of the plants that have these leaf structures, and then turn in your lists on Friday. It’ll be quite easy for you to find examples of the alternate leaf structure because, as I said before, this is the most common type on leaf structure. It’ll be a bit more difficult to find examples of the opposite structure, but by far the most difficult leaf arrangement for you to find will be the whorled structure because this leaf arrangement’s so rare. You’ll have to spend some time finding examples of the whorled leaf arrangement in our botanical garden. See you on Friday with your lists…eh…uh…Hold on for a minute! Just a word of warning…You’d better not put off the assignment until Thursday evening, as I’m sure many of you are used to doing. The botanical gardens close at sunset each day, so if you try to put this assignment off until Thursday evening, you won’t be able to get it done. 第三十八篇 , Hello, Dr. Trent. , Hi, Sandy. Come on in. is there something you wanted to talk about with me? , Yes, it’s about the project in music class. , I thought I explained it pretty well in class,…but, what’s your question? , Um…I’m just not sure what you want me to do for the project. , I think I explained it clearly in class…You were in class, weren’t you? , Yes, I certainly was. , Well, then, why don’t you tell me what you heard about the project. , OK. I know you said that we should choose a composer. , Yes, that’s right. , Well, does it have to be a composer that we’ve talked about in class, or can it be a different composer? , I think the project’s a bit easier if you choose one of the composers from class, but you really can choose any composer for the project. , OK. , So do you have a composer in mind? , Yes, I do… , And is it one of the composers from class? , No, it’s not… , That’s OK…now what are you supposed to do for the rest of the project, after you’ve chosen a composer? , The next step is to research the composer. I haven’t started the research yet, but that doesn’t sound too bad 20 to me. , And what’re you supposed to learn about the composer? , I know we were supposed to learn about the composer’s style…his style of writing music. , Yes, exactly. , But are we also supposed to learn about him—I mean about his life? , Some background about his life would be helpful, but really, the focus is on the composer’s style of writing. Is that clear? , Yes, it is. , And now for the final part of the project. What are you supposed to do for the final part of the project? , That’s the hard part, if I understood you correctly in class. , Well, it’s the most interesting and challenging part, I think… , We’re supposed to write a short piece of music in the style of this composer. , Yes, that’s right. , That’s a lot harder than doing some research. When you do research you just have to find things, but in this part of the project I have to create something on my own. I’m not sure I can do that. , I’m sure you can. Keep in mind that it’s just a very short piece, but it does have to be in the style of the composer you’ve chosen. , That’s what I thought you said in class…but it sounds so hard. , It’s s challenge, maybe, but I’m sure you’ll enjoy it once you get into it. 第三十九篇 , Today we’re going to be reviewing some information about the Great Lakes, and we’re going to see that traditional beliefs about the Great Lakes do not reflect scientific reality. First of all, can you identify the Great Lakes on this map? Hannah? , Lake Superior is the largest ad northernmost of the five Great Lakes. The two smaller lakes to the southeast of the other lakes are Lake Erie and Lake Ontario. The two lakes in the middle are Lake Michigan and Lake Huron. , All right. Now I’m going to ask a question that sounds like an easy question but really isn’t. This deceptively easy question is, which of the Great Lakes is the largest? Jack? , It seems like an easy question because, on the map, you can clearly see that Lake Superior is the largest, and any almanac of world information lists Lake Superior as the world’s largest freshwater lake. But I know Lake Superior really isn’t the answer you want. , And do you know why Lake Superior isn’t the answer I was looking for to the question about which Great Lake is the largest? , Yes, I think so. I believe I read that scientists who have studied the interactions of the lakes have found that Lake Michigan and Lake Huron actually interact as one lake. , That’s exactly right…So, in reality, which of the Great Lakes is the largest? , In reality, Lakes Michigan and Huron together are one lake. You could say that Lake Michigan-Huron is the largest of the Great Lakes and the world’s largest freshwater lake. , OK. Now, let’s go over the arguments for considering Lake Huron and Lake Michigan one lake rather than two, Pat? , Well, first of all, Lake Huron and Lake Michigan are at the same elevation, and they are connected by the Mackinac Strait, which is also at the same elevation. If they were two distinct lakes, they might be divided by 21 a stream or a river. However, the Mackinac Strait is not a stream or a river. Instead, it is a body of water that is 3 to 5 miles wide, wider than most lakes. , That’s right. So what does this mean? , Mackinac Strait is not a river that separates two lakes; instead, it could be argued that there is one giant lake, Michigan-Huron, and this one giant lake narrows at the spot known as Mackinac Strait. , No bad at all, Pat. I couldn’t have done better. Now let’s see if some of the rest of you can match that. What about you, Hannah? What about the flow of water between Lake Michigan and Lake Huron? , The flow of water between the two lakes can reverse. Whenever there’s an imbalance in the water levels in the two lakes, the water levels can equalize rapidly, in either direction. , Very good, Hannah. And what does this mean? , It means that if the water level becomes higher in Lake Huron, water will flow from Lake Huron into Lake Michigan, and if the water level becomes higher in Lake Michigan, water will flow from Lake Michigan into Lake Huron. , So the flow of water between the two lakes can move in either direction, from Lake Huron into Lake Michigan or from Lake Michigan into Lake Huron, and the water levels in Huron and Michigan will always equalize. What conclusion can be drawn from this information? Pat? , This means that the two lakes, Michigan and Huron, are, in reality, acting like one lake instead of two. , Exactly. You seem to have a good understanding of this material. I’ll see you at the next session. 22