Chalking

Do you know how a house is built? With a triangle, a rectangle and a piece of chalk. And, do you know what can be done with a triangle, a rectangle and a piece of chalk? Yes, a pine. Do you know how a tree is built? With a circle, a rectangle and a piece of chalk. And, do you know what can be done with a circle, a rectangle and a piece of chalk? Yes, a gentleman or a lady.

One more question: Do you know how to build a thousand-story building in a big city? With a large rectangle and two smaller ones and a piece of chalk. And one last question, do you know what can be done with three semicircles and a piece of chalk? Yes, a car.