How do you create depth on a piece of paper? A. Create a foreground, mid-ground, background
B. All answers apply
C. Use a variety of sizes
D. Overlap

Overlapping : Overlapping the objects in your illustrations can help to create a sense of depth. With this technique, smaller, farther objects in the background are placed behind larger objects in the foreground, making them feel like they are a greater distance away from the viewer.

i think it's about 10 mins.

actually i think that's wrong, but i don't know how to delete this.

but who knows it might be right.