What new approaches to form did the impressionists introduce and how were these trends continued in the work of the post-impressionists?

The new approaches to form that the impressionists introduce were:

-Color theory (in light and nature)

- added brown or black color

-Object shadowing

- 'en Plein air' (painting outside)

as for the post-impressionist, they still adopted these techniques, but they add more emotion and personal insight into their artwork.