Scale usually sets the tone of art work. Scale can influence how funny, sad or serious a piece can be.

Naturally if you see a picture with two objects and one of those objects are significantly bigger than the other its a sign of dominance or conquer. In this particular picture the ginormous blackboard is covered with complex formulas. The young lady seems to have solved something overwhelming difficult. She seems to have taken a step back just to analyze her success in solving or creating something bigger then herself.