Our assignment was to take 2 pictures of a subject. One without any comparative element for scale and one with.
For this picture, I focused in on this tall tree near the red brick. I took it because a tree is a good object to show scale with. Even though you can the tree in this picture, you can't really tell how big it.
Now in this picture, you see that Brian is a part of the image and is there to be compared to the tree in terms of how big it is relative to him.