A student produces "Is there place in this car for three people?"
It's clearly an error not a slip and it's quick to correct so I'd probably correct it.
Now's a good time to give a mini-lesson on the differences between 'place', 'room', 'seat' and 'space' even though I'm teaching pronunciation right now.
This is serious so I must correct.
This is just a slip caused by tiredness or whatever. I'll ignore it.
A student produces, "I him to go see not now then."
Now's a good time to review all the tenses the student should know.
I need to find out what was meant and try to provide the language needed.
I'll tell the student that she's got something wrong here.
I'll ignore it.
A student produces, "She was a nurse so she gave the injured man the kiss of his life."
I'll tell the student that she's got something wrong here and get everyone else to see if they can correct the expression.
Now's a good time to review the article system with her.
I'll ignore it.
I need to correct this gently without falling off my chair laughing.
In a role play at the end of a lesson about restaurants, a student produces "Excuse me Mister Waiter".
Now's a good time to stop the role play and give a mini-lesson on the different ways cultures in my classroom talk to service assistants.
I need to intervene.
I'll ignore it.
I'll make a note and correct it at the end because it only happened once.
In a discussion about travel experiences intended to practice "I have / haven't ever been to ..." a student produces, "It was a terrible weather."
I'll tell the student that she's got something wrong here and get everyone else to see if they can correct the expression.
Now's a good time to review countable and uncountable nouns.
I might make a note and sort this out later if I have the time.