prepositions

Is it correct to say sitting in a chair or should it technically be sitting on a chair? Can one sit in a solid object like a chair? I understand sitting in a house or box or car.

[David L.]

You would sit in an armchair, where the body is partly enclosed by the arms of the chair and the broad, high back. We even talk about 'sinking into a comfortable armchair and putting my feet up."

With a dining room chair, or any flat-base chair (the kind of chair with a flat sheet of wood for sitting on), with either no arms, or just wooden arm rests; and an open back rest, then we sit 'on' sit a chair, just as we would sit on a stool.

In a classroom situation, we would say, "Sit in your seat."