Maybe my english dialect is weird, but we would never sit "on" a chair, we sit "in" a chair. On makes it sound like youre sitting on top of it with your feet in the seat.
"Sit on a/the chair" sounds fine to me.
I'd agree. I get the feeling the on/in decision is regional, as in Scotland I'd say 'sit in a chair'. Perhaps both should be accepted.
Brit here, We sit 'on' chairs, not in(side) them.
Turn the chair the right way up and you can sit IN it rather than making like a human pencil topper on one of its legs...
You're always sat 'on' top of a cusion but I guess you can sit 'in' some chairs like sofa's for instance.
Can it also mean "I sit down on a chair?" (I'm neither a native English nor Japanese speaker, so bear with me)
Yes, it can. It's basically the same.
"I sit on chairs" is supposedly wrong... Why?
I don't think it's wrong... give that one a report if it still is not accepting.
Look at Mr. Important over here! He sits on a chair! フープティードゥー！ I bet you eat expensive meat, too.
OK, this was funny.
What's wrong with "I'm sitting on a chair"?