Shallow Depth of Field

In this picture, a girl is hiding behind the bushes spying on the boy standing up. The girl is meant to be out of focus while the boy is in focus. She is farther away from the camera and the boy in focus is closer to the camera.
I wanted the girl to stand behind the bushes to look like she was waiting to surprise the boy. Chase looked preoccupied with the leaf that he was playing with and the surprise would have been fnnier. This shot was slightly as I caught Chase in this position and I just told Joanne(the model) to go behind the bushes and scare him.
This assignment was a bit of a challenge because I had to reshoot. I didn't get how the objects had to be to become shallow depth of field. The outcome of my first attempt made everything in the pictures blurry. Reshooting this assignment was a hassle because I only 6 shots to shoot with and if I had a chance to reshoot shallow depth, I would. I have grown to like using shallow depth of field and I'm now trying to incorporate it in my future assignments as a form of practice.