Are my sentences correct?

[Arefeh]

I paused the DVD at excited scenes.
The students were supposed to summerize the chapters that they'd already read!
If i were him,i would have asked the students to guess what would happen next instead of asking them to summerize the story.
I used a pice of paper in order to cover a half of the screen to make the students guess what would happen.
And another question:
Could you mention the most common expressions and sentences that a teacher would use when she enters a class for example for greeting except hi/how r u?/how are you doing?/what's up?
And one more question:
Where and in which sites can i find the activities that is good and interesting for using in an english class?And how can i make teaching grammar more fun?
Thanks beforhand.

[vv0510_vn]

I paused the DVD at excited scenes.
The students were supposed to summerize the chapters that they'd already read!
If i were him,i would have asked the students to guess what would happen next instead of asking them to summerize the story.
I used a pice of paper in order to cover a half of the screen to make the students guess what would happen.
And another question:
Could you mention the most common expressions and sentences that a teacher would use when she enters a class for example for greeting except hi/how r u?/how are you doing?/what's up?
And one more question:
Where and in which sites can i find the activities that is good and interesting for using in an english class?And how can i make teaching grammar more fun?
Thanks beforhand.

Hello,
Here's my opion: (As far as I know )

+ summerize ==> summarize
+ If i were him,i would have asked the students to guess what would happen next instead of asking them to summerize the story. ==> If I were him, I would ask the students to guess what would happen next instead of asking them to summarize the story.
+ pice ==> piece

=========

Some expressions:
+ Good morning/afternoon/evening class.
+ Nice to see you all again.
+ What's going on?
+ Where did we work out?
...