Three Hands, Two Holding Forks, Nuenen: late March-early April, 1885. Images © Stichting Van Gogh Museum.
Form is a three dimensional geometrical figure (ie.: sphere, cube, cylinder, cone, etc.). There are two types of Form: geometric – a skyscraper and natural – the hands above. Whereas Shape is two-dimensional, or flat, like the drawings you created while interacting with Line.
The illusion of Form on paper is created by using Value, the relationship between light & dark. Value will define objects depth & perception. For example, the drawing by Van Gogh above uses Value to create the three-dimensionality of the hands.
Interact with Form & Value