下面是某英语教师在写作课的教学片段，阅读并回答问题。
Tell students we would write an article for our favorite sports, and the topic is about sports.
Show students a model article on the screen and lead them to find out the format of an article: main heading, smaller heading and the body.
Run a brainstorming activity: show some pictures about the sports and the famous athletes.
Ask students the questions as follows.
Why are you interested in that sport?
Who is your favorite athlete ?
What do you do to improve your skills?
Then I would ask them to have a discussion about the above questions. They can change their ideas with their partners and find out the similarities and differences. Then choose one idea to write with. After the discussion, I would pick some students to report their topics at the front.
根据上面的课堂教学片段回答下面三个问题：
(1)该片段属于什么教学环节？体现了哪种写作教学模式？
(2)请从写作教学原则的角度，评价该教学片段。
(3)该片段中教师的课堂角色有哪些？