Something like positive and and negative interpretation. We had to draw an item and color the background leaving the object blank white. (Teacher doesnt know that its already white. Hehe.)

A contrast exercise? If so I would suggest using a darker blue to show a bigger gap between "positive" and "negative". Make sure your strokes are even in pressure as well. Until you can get a familiar feel for the brush in your hands I also recommend painting in only one direction to keep the image of control. Very nice job. You were able to control the paint from bleeding into the symbol which is also very clean and pretty!