The size of a shadow decreases when the object is moved closer towards the screen. The size of a shadow increases when the object is moved towards the light source.
Answer to the question: How?
Explanation how the size and shape of a shadow depend on the distance of the light source or screen:
Shape of a shadow: The size of a shadow depends on the angle in which light falls on it or the shape of the part of the object that blocks the path of light.
Size of a shadow: The size of a shadow is long when the light source is placed along the length of an object and it is short when, the light source is placed along the width of an object.