There weren’t enough chairs so we had to sit on the floor.
On fire (If something is burning we say it’s on fire)
Get the fire extinguisher! The curtains are on fire!
Look! Dave is on fire!
On the way (If we do something while we are travelling somewhere we do it on the way)
I don’t have any bananas, I’ll pick some up
on the way home from work.
We stopped for lunch on the way to our hotel.
On a bus, train, boat, plane (If we can stand up in a vehicle we use the preposition on)
It’s rush hour, there are so many people on the train!
I envy people who can sleep on a plane. I can’t even take a short nap, it’s not comfortable in Economy class!