Polygon Tool is creating a circle, not a polygon

When I click and drag (and hold down the mouse ) to create a polygon. It appears as though it's creating a circle. I have tried pushing the arrow key down, while holding the mouse simulataneously but it seems to be increasing my shape in tiny increments ( probably 1 pixel at a time )  What did I do? How do I make it go back to behaving like the polygon tool is supposed to.

I know it's not actually a circle, rather a polygon with so many sides it appears as though it's a circle. I don't know how to reset the tool.