Intervening with magic with muggles nearby would be ridiculous, I'd convince the bystanders to help me break up the fight.
I'd step in and help if I knew the person being threatened, even if it means having to blow my cover as a wizard.
I'd charge right in telling them both to stop.
I'm not much of a fighter, so I'd call the muggle police.
I'd talk to the group of friends I'm with and we'd work out a way to help.
Secretly point my wand and non verbally disarm the man with the knife so that the other man can get away, then leave the scene quickly before anyone notices my presence.
I'd walk around them; I'm on a night out and by law I'm not meant to use magic to help, so there's no reason to hang around when I could be enjoying myself with friends elsewhere.
I wouldn't even spare them a glance.
I would suggest to one of the muggles that they phoned their police service and took a picture of the men, before leaving.
I'd join the crowd and watch to see the outcome
I'd hop into the fight at the last minute, so I have less chance of injury but will get some of the glory.
I wouldn't get involved in the fight, but I'd stay just in case someone got seriously hurt so that I could help them. In that situation, Magic must be allowed.
I'd have to assess the situation first. It might not be as it appears, the man with the knife is not necessarily the attacker.
I'd call the police and wait there to give my statement. They might want help identifying the men, and they're unlikely to suspect that I'm a wizard if I don't do anything.
I'd distract the man with the knife with a taunt so that the other man could overpower him.
An icy Forest
A dense Jungle
Rolling green hills
A leafy canopy
In front of the fireplace
A Tropical ocean
A flowing river
On the Sea bed
A coral Reef
A frozen tundra
On a Moor
The open Sky
A mountain range
In the treetops
In a Thicket
Failing to achieve something
Seeing someone you love get hurt and not being able to stop it
People who deliberately hurt others
Getting an answer wrong
Being kept in the dark about something
Missing an opportunity
People who are inconsiderate
People who are two faced / lie
Being told what to do
Their tactical thinking
Their ability to love
Their sense of justice
Their cooking skills
Their sense of team spirit
Their sense of humour
Their knowledge of the world
Their sense of compassion
Their even temper
You were one of the ones who organised the prank, so you don't say anything.
Say nothing, I trust that my friend probably had a good reason to do something so dangerous
Tell the teacher, you wouldn't want to be friends with someone who endangers the lives of others for a stupid prank anyway.
Carry on sleeping on your desk and leave the decision to someone else.
Stand by your friend, but after class tell them that they should have confessed.
Say nothing, then when the class ends approach binns and tell him who it really was, thus making sure the right person is punished and you stay on good terms with your friend.
Congratulate your friend on a successful prank and carry on working, the expulsion is probably an empty threat. Either way it doesn't affect you.
You don't even look up from your work.
You decide that although the person Binns is accusing is innocent, he would not be getting expelled if he didn't have a history of doing much worse than this. So you stay silent.
You just sit back and watch the show, wondering who will lie to Binns and who won't.
The boy who is accused has a rich father and will not forget you helping him out of a tight spot. You take the blame yourself, making him grateful to you whilst still keeping the friendship between you and your friend intact.
The person who Binns is blaming will be expelled if nobody confesses, so you take the blame. You have a clean record and will only be given a detention.
Be disappointed in your friend, but say nothing to the teacher because you suspect someone else will soon tell the the teacher the truth.
Wait for someone else to say something, or for Binns to figure it out for himself.
Laugh and carry on talking to those near you. Binns will soon forget the whole incident, as he always does.
The ability to freeze time
The ability to imitate anything you saw just once perfectly
The ability to never forget anything
The power of suggestion (making people do what you want)
Drawing the future