We used G3 iMacs with the puck mouse until high school. You can't convince me it was the epitome of ergonomics.
They were an upgrade from the Mac LC II. I don't recall those having very big screens either.
15" and 4:3 was about as big as it got in high school. A computer on a table and we sat on a normal plastic school chair.
And the flicker. It was pretty bad on most screens.