下面是某教师的课堂教学片段。
Step 1 Revision
（互相问候后，教师将装有彩色小图片的信封分发给各小组）
T:Open the envelopes please. You have something nice in them. What are they？
S:A green ear，a red ball，a blue plane，a yellow cat...
T:What do you like？
S:I like..…
Step 2 Lead-in T:Let's sing the song Who Is Wearing Yellow Today.（音乐结束后，教师并没有停下来，而是改编歌词继续唱）
T:Who is wearing blue today？Blue today？Blue today？Who is wearing blue today？
Step 3 Presentation T:Who is wearing blue today？
S:You are wearing blue today？
T:Yes，I'm wearing blue today.I'm wearing a blue sweater now.
（学生跟读sweater，sweater，blue sweater）
T:I like the blue sweater.If you like it，please say it out loudly.
T:Do you like the pink sweater？（PPT展示粉红色毛衣图片）S:Yes，I like the pink sweater.
（借助学生的穿着，引出jacket等新词，展开活动）T:It is too hot.I will take off my sweater.Please take off your jacket.
（伴随动作，依次教授词组take off，put on，hang up and put away）
请根据材料回答下列两个问题。
（1）教师在复习、导入以及呈现环节创设了不同的情境，请分别对其创设方法及作用进行分析。（15分）
（2）评析教师在语言学习活动中的角色。（15分）