Ask the students to go through some facts of cloning.

T: From these facts we know human beings have achieved great progress in cloning. Now read the text carefully to get the answers for these questions: what animals have people cloned?

S: Frogs, mice, cows, sheep, bison, cats, and dogs.

T: Good job. Answer the question: What are the common characteristics of these animals?

Ss: They are nowadays animals.

T: Yeah, I think you must have seen the film Jurassic Park, in which a scientist clones several different kinds of extinct dinosaurs. Can we really clone dinosaurs now?

Let the students turn to page 15 and then read the text quickly.

S: We cannot clone dinosaurs, because it's difficult for us to get its DNA.

T: Good job. It's only a dream. Dinosaurs disappeared 65,000,000 years ago. So the chance of dinosaurs ever returning to the earth is merely a dream.

Step Ⅱ Read and answer (P16)

To answer the questions, teacher can give the students some examples as explanation, for example, Question 1.

T: Now think about this question: if in the world there is only one sheep and human beings want to clone more. Some days later a Dolly appears, then many more. But one day all sheep get the same deadly disease. Now please think about what the results are. S: Maybe they would all die.

T: Why?

S: Because all sheep have the same arrangement of genes.

T: Right. Now can you answer Question 1? Why shouldn't you clone an extinct animal unless there is enough diversity in the group?

S: It is useless to clone an animal if there is not enough diversity in the group for it to overcome illnesses.

T: Why is it wrong to clone an extinct animal if it would have to live in a zoo?

S: If the cloned animals have to live in the zoo, it is unfair to them. They need freedom.

T. Why can't you clone the DNA of animals that have been extinct longer than 10,000 years?

S: Dinosaurs disappeared 65,000,000 yeas ago. So the chance of dinosaurs returning to the earth is merely a dream.

Step Ⅲ Discussion (Question 2)

Ask the students to have a discussion in groups, organize their words properly, and give vivid description of the chosen animals.

T: Now look at the table on page 16, discuss in pairs which extinct animals described are worth restoring by means of cloning. Choose one animal and use the information to help you argue why this animal should be restored to the earth.

Give the students six minutes to discuss.

S1: I think Great Auk is a wonder. Because it is a very large bird that cannot fly. The useful thing about it is that its feather doesn't absorb water. I think if we wear clothes made of its feather, we will not worry about rain.