At 33 million miles to the millimeter, the about 4000 million miles from the sun to Pluto would be around 120mm. Just beause you had an error in your calculation doesn't imply that either your teacher nor science as a whole are wrong.
It's possible I am misremembering the exact numbers from many years ago. But that doesn't change the fact that any accurate model of the scale of the solar system would not have fit in the classroom (and certainly does not fit on the pages of a book). There are scale models of the solar system in the world. They get laid out across several city blocks and things like that. One of them puts something (a star maybe? -- not something within the solar system, I don't think) in Australia when the model of the solar system itself is in some place like Great Britain.
