Some scenarios where the above will come in handy::
It's the first day of school and you have 5 crying children who haven't learnt to separate from the parent yet.
One child cries and sets up a chain reaction.
There's a new child who has separation anxiety and you're trying to teach while he sits next to you crying noisily.
You're reading to a group and one child puts up her hand to say something. You think she's going to comment about the story but she tells you something unrelated like what she had for dinner.
All the children need to go to the toilet at the same time.
A child has a little 'accident' while you're teaching.
The students stare back at you blankly after you have spent the last 10 minutes teaching.
There are so many other scenarios that teachers face. Can you think of any other?