more closely. If they?re the right species, they could help solve one of the greatest extinction mysteries of our time.

Dr. Lockwood: “To get my hands on the body, in terms of this murder mystery, was critically important.”

Narrator: A look under the microscope reveals the signs.

Dr. Lockwood: “At that moment, I knew that we had the Rocky Mountain locust.” Narrator: It?s an exact match. They?re the same species of locusts that once devastated the American plains. Lockwood?s study of the Rocky Mountain locust has told him more and more about this odd insect. They seem to have split personalities. On one hand, as members of the grasshopper family, they?re generally shy and remain alone. But when annoyed in just the right way, the once gentle locust changes completely into some kind of destructive monster. They change color and their wings and legs grow longer. Eventually, they become more aggressive and swarm, whereby they become a kind of living, breathing weapon of mass destruction.

Dr. Lockwood: “Nobody?s in charge. There?s no leader, there?s nobody out in front.” Narrator: Back in the laboratory, the locusts are revealing their secrets. The DNA test results are back and they?ve indicated one certain fact: the Rocky Mountain locust didn?t decline over a long period of time.

Dr. Lockwood: “It was not sort of a death by old age. In fact, what we?re looking at is a very sudden sort of ?bolt out of the blue? disappearance. There?s nothing in the genetic course of this species that would lead us to believe that it was in its last days.” Narrator: Some other force must have been responsible for destroying the plague, and Lockwood is determined to find it.

Dr. Lockwood: “I began to realize that we?ve been looking at the wrong scale. If we want to find out perhaps what eliminated the Rocky Mountain locust, what we should be looking for is what was happening to the species at the time of its weakest link.” Narrator: Now, after years of research, Lockwood may finally be able to solve the mystery of why the Rocky Mountain locust disappeared. It turns out that the Rocky Mountain locust gathered in one particular region to lay its eggs. In the 1800s, that region was in the river valleys of the Rocky Mountains.

Dr. Lockwood: “It turned out that agriculture was booming in these river valleys in the late 1800s.”

Narrator: The gold and silver industries were booming as well. The major nesting area of the rocky Mountain locust had become a busy and overcrowded place; therefore, conditions there would certainly have had an effect on any species.

Dr. Lockwood: “The killer of the Rocky Mountain locust turns out to be us. The pioneer agriculturalist of the Rocky Mountain West in the late 1800s is the killer of the Rocky Mountain locust.”

Narrator: As farms appeared in the river valleys to feed the miners, the farmers plowed up the fields and stamped out the delicate eggs that had been laid by the great swarm. By not allowing the eggs to mature into full-grown locusts, the species was entirely destroyed at its weakest — when the insects were just eggs. The only extinction of a pest species in agricultural history was in fact an accident. Teaching notes

I. 1. Give students time to go through the statements. 2. Play the video.

3. Elicit the answers from students.

4. Have students discuss why the statements are true or false. II. 1. Allow students some time to predict the answers. 2. Play the video.

3. Elicit the answers from students.

4. Have students summarize the main idea of this part. III. 1. Explain how to conduct an interview.

2. Have students read the useful expressions.

3. Put students into pairs and have them discuss the interview questions and answers.

4. Have some pairs role-play their interviews to the class.

5. Give students some comments and suggestions for improvement. Word bank

1. disastrous adj. causing great damage A disastrous fire swept through the factory. He made a disastrous mistake.

2. combination n. a number of separate things or people that are combined to form a single unit or whole A combination of drought and locusts forced people to leave their hometown. 3. destructive adj. causing great and irreparable damage The storm could be destructive to the crops. Useful expressions Expressing surprise * Oh, my! * Incredible! * Unbelievable! * What a surprise! * How could it be?

* I couldn?t believe my eyes. Teaching notes

I. 1. Have students read the statements to get familiar with the ideas. 2. Play the video.

3. Elicit the answers from students.

II. 1. Give students time to predict the answers. 2. Play the video.

3. Elicit the answers from students.

III. 1. Have students read the useful expressions.

2. Put students into pairs and have them prepare the explanations. 3. Have some pairs present their explanations to the class.

4. Give students some comments and suggestions for improvement. Word bank

1. investigate vt. try to find more information about

If you hear such a rumor, investigate it first. It?s not easy to investigate such a mysterious case.

2. tremendous adj. very great in size, amount or degree There was a tremendous series of forest fires. He inherited a tremendous amount of money from his uncle.

3. specimen n. an individual animal, plant, etc. used as an example of its species or type for scientific study or display They are in search of a special specimen of butterfly. There are many specimens of copper ore in the lab. Useful expressions

Expressing determination * I have decided to...

* I?ve made up my mind to... * He was determined to... Teaching notes

I. 1. Give students time to predict the answers. 2. Play the video.

3. Elicit the answers from students.

4. Have them retell the activities carried out by Dr. Jeff Lockwood. II. 1. Give students time to predict the answers. 2. Play the video.

3. Elicit the answers from students.

4. Have students ask and answer these questions in pairs.

III. 1. Have students repeat each sentence after it is spoken twice and then write the sentences.

2. Have students listen again, and mark the word stress on content words with a stress mark (?).

3. Have students listen to each sentence and draw an upward arrow ? for rising intonation, or a downward arrow ? for falling intonation.

4. Have students listen again and draw a curved line ? to mark any words that are linked or blended together.

5. Have students practice reading the sentences till they can say them using appropriate intonation and stress pattern. Word bank

1. reveal vt. show or allow (something previously hidden) to be seen He has successfully revealed the exact reason. The DNA analysis reveals everything.

2. aggressive adj. always ready to quarrel or attack The grasshopper turned out to be very aggressive. The aggressive animal attacks anything that it meets. 3. eliminate vt. remove or get rid of completely The government tried its best to eliminate poverty. Teaching notes

I. 1. Give students time to predict the answers.

2. Play the video.

3. Elicit the answers from students.

II. 1. Give students time to predict the answers. 2. Play the video.

3. Elicit the answers from students.

III. 1. Have students read the useful expressions.

2. Put students into pairs and have them discuss the reasons, make comments and express their feelings.

3. Have some pairs present their discussion results to the class. 4. Give students some comments and suggestions for improvement. Word bank

1. turn out happen to be or be found to be It turns out that it's human beings who eliminated the Rocky Mountain locust. She turns out to be the mother of the abandoned child. Collocation

turn away 不准…进入 turn down 调低；拒绝 turn in 交还；获得 turn off 关掉 turn on 打开

turn to 转向；向……求助

2. boom vi. grow rapidly in activity, value or importance The economy is booming. California boomed when gold was discovered there.

3. delicate adj. needing careful handling, especially because easily broken or damaged We need to be careful of the delicate vase. Teaching notes

I. 1. Give students time to predict the answers. 2. Play the video.

3. Elicit the answers from students.

4. Have students summarize the main idea of the entire video. I. 1. Have students read the useful expressions.

2. Put students into pairs and have them talk about the picture.

3. Have some pairs role-play their conversations in front of the class. 4. Give them some comments and suggestions for improvement. III. 1. Put students into groups of three or four. Introduce the task. 2. Go through the information in the table.

3. Give students time to do the research, find the information and complete the table.

4. Invite a representative from each group to report to the class. Encourage groups to prepare PowerPoint presentations of their findings.

5. When a group is making a report, ask other groups to take notes.