"Biological Invaders" teaching design materials

Teaching objectives

1. Accumulate through self-reading and grasp the main content of the explanation in this article;

2. Master the basic sequence and method of explanation;

3. Cultivate students’ scientific spirit of seeking truth and improve students’ environmental awareness.

Teaching focus

Understand the common explanation sequence and the role of explanation methods.

Teaching process

1. Introduction of new lessons

Have you noticed that the riverside where sea salt used to be covered with aquatic plants is now occupied by water hyacinth? . This water hyacinth was introduced to my country as an ornamental plant in the 1980s. Due to the suitable environment and no natural enemies, it grew wildly everywhere and eventually became a biological invader, causing great losses to agriculture and aquaculture. Indeed, ecological issues are the central issue of environmental issues in today's world.

Let’s study "Biological Invaders" together, hoping to improve our awareness of protecting the ecological environment.

2. Overall perception

1. Students read the text quickly;

2. Word learning:

Unbalanced robbery (lǜe ) Fan (fán) fence blame (jiù) colorful

Xiao gathers in the mountains and forests to inhabit, helpless, natural selection, indifferent to misfortune (è) fate

3. Initial perception:

< p>What is the object of this article? Biological invaders

3. Read the text

1. Can you outline the sentences that reveal the meaning of "biological invaders" from the text? < /p>

Biological invaders are organisms that originally lived in a foreign country and migrated to a new ecological environment through unnatural means.

2. Why does the author not say "migration" but "invasion" for these organisms?

They will not only destroy the original ecosystem of a certain area, but also may It has caused immeasurable economic losses to human society.

3. What is the order of explanation used in this article?

This is an explanatory article, which is explained in a logical order. The article first explains the concept of "biological invaders", and then introduces its hazards, causes, people's opinions, and measures taken, which is in line with people's thinking rules.

IV. Understanding the explanation methods

1. What explanation methods are used in this article to specifically introduce the hazards of "biological invaders". Please give an example.

This article uses illustrative methods such as listing numbers, giving examples, and making metaphors.

2. Find relevant sentences that use the above explanation method, and talk about the benefits of using it this way.

Numbers listed:

⑴ Since World War II to the present, 9 of the 11 species of birds native to Guam have been driven to extinction by brown tree snakes, and the only two remaining species of birds are also fighting against It is decreasing day by day and is in danger of extinction at any time. ─In just the sixty years since the 1940s, Guam's bird species have dropped from 11 to 2 species. The change in this number clearly illustrates the harm of "biological invaders" to the natural ecology.

⑵ So far, billions of dollars have been spent cleaning and replacing pipes. In the United States alone, the annual economic losses caused by "biological invaders" are as high as more than 200 billion U.S. dollars--which shows how harmful "biological invaders" are to human beings.

Examples:

⑴ Dandelions and fish and shrimps in mountain streams──In the early days of human civilization, land and navigation technology were not yet developed, and the ecological balance in nature was not affected. Too much damage;

⑵ The invasion of North America by European spotted clams, Asian longhorned beetles and South American red ants - "biological invaders" have brought huge harm to humans;

⑶ The brown tree snake is almost extinct and Guam’s birds are ─ the “biological invaders” destroy the natural ecology;

⑷ Fresh fruits and vegetables, transnational pets ─ are the human causes of the “biological invaders”; < /p>

⑸ The U.S. House of Representatives passed the strengthening of cross-departmental monitoring of vehicles that may carry alien species. At present, all countries have taken corresponding measures to deal with "biological invaders".

For example:

⑴ Biological invaders - this type of "invasion" and "immigration" can cause harm to humans and nature;

⑵ Stowaways ──Highlighting the unknown nature of his behavior and quietly causing harm to mankind;

　⑶ Taking a "free ride" across trade──very vivid.

5. Experience expansion

1. What other biological invaders do you know in nature?

Canada goldenrod, piranha, etc.

2. What should we do if biological invaders are found in real life?

(Students can speak freely)

6. Class Summary

This is an explanatory article about ecological issues.

It explains to us what biological invaders are and the huge harm caused by biological invasion, prompting us to be highly alert to this special ecological phenomenon. We not only acquire certain ecological knowledge, but also develop a sense of responsibility to society. In addition, the text is well organized and uses the methods of listing numbers, examples, and metaphors to provide reference for us in writing expository essays.

7. Assign homework

1. Require students to use three explanation methods: listing numbers, giving examples, and making analogies to explain chalk;

2. Extracurricular Share the information you collected about biological invasions, and then present it to the class;

3. Complete the "Chinese Workbook".