Sarah wanted to see which of two new toys (a puzzle and a block set) her preschool class enjoyed playing with most. She observed how often each toy was played with every day for one week and
recorded the total number of minutes per day each toy was used.
Independent
Variable
Dependent
Variable

The linear perspective changed the quality of art because it gave art a sense of reality. it gave the illusion that the background and surroundings were actually close and/or far and a sense of depth. linear perspective change the quality of art following its birth the renaissance period as they want the art to be more realistic and they believe one way to achieve it is to use the method of linear perspective. it uses the principle of math to realistically portray space and depth in art. 

What painting? can you post a picture

I'm sry but which example?